I have a ruling to make. The inquest into Mr. Litvinenko was formally opened at 11 o’clock this morning and immediately adjourned. In view of the Home Secretary's statement and the general public interest, I am exercising my discretion to waive strict application of the sub judice rule, but I ask hon. Members to bear it in mind that an inquest has been opened.

With permission, Mr. Speaker, I will make a statement on the death of Mr. Alexander Litvinenko. This statement provides an update on the circumstances surrounding his death on 23 November 2006. As I made clear to the House on Monday, Mr. Speaker, and as you have again made clear, I remain limited in what I can say, in order to ensure the integrity of the police investigation and to observe the relevant proprieties. I continue to work with my colleagues across government to ensure an appropriate response to the developing situation, and I am grateful in particular to my right hon. Friends the Foreign Secretary and the Secretaries of State for Health and for Transport for their assistance.

In my previous statement, I highlighted the issues being addressed by the Government in response to the death of Mr. Litvinenko. I confirmed that traces of the radioactive isotope polonium-210 had been found in Mr. Litvinenko’s urine, and at several London locations. To date, some 24 venues have been, or are being, monitored, and experts have confirmed traces of contamination at approximately 12 of these venues. Police continue to trace possible witnesses and to examine Mr Litvinenko’s movements at relevant times. It is probable that the investigation will continue to bring additional locations to our attention for screening—additional, that is, to the numbers that I have just given to the House. I stress that the Health Protection Agency continues to reassure members of the public that the risk of exposure to this substance remains low.

At 23.00 hours last night, NHS Direct had received approximately 1,700 calls. A total of 69 people have been referred by NHS Direct to the HPA as a precaution. Fifty-two of those people have been contacted, 18 of whom have been referred to a special clinic or to an appropriate clinic in their area. To date, 29 urine tests have been returned, and none of the results shows any cause for concern. I hope that that helps to reassure the public on these issues.

Earlier today, as you mentioned, Mr. Speaker, the coroner opened the inquest into Mr Litvinenko’s death, which was formally adjourned pending further scientific evidence and investigation by the police. The post mortem is expected to take place tomorrow. As confirmed last night, two British Airways aircraft are being monitored by experts at London Heathrow. I can confirm that early results show low levels of a radioactive substance on board both aircraft. The HPA expects to be able to confirm that no residual public health risk remains on the first plane. A formal report is in progress, and measurements continue to be taken on the second plane. The risk to public health is, we believe, low, but passengers who wish to receive further advice should in the first instance contact the special helpline or website set up by British Airways to confirm that they were on one of the aircraft. If they were and they are concerned, they should contact NHS Direct for further advice.

A third BA aircraft is on the ground at Moscow airport. BA has decided not to return it to London until the position is clearer, and the Government are in contact with BA about the next steps. Between them, these three aircraft have made some 221 flights, involving about 33,000 passengers and approximately 3,000 staff. A fourth aircraft of interest—a Boeing 737 leased by Transaero—arrived at London Heathrow terminal 1 this morning. Passenger details will be collected and the HPA will contact individuals if any matters of concern are found.

The Foreign Secretary spoke to the Russian Foreign Minister on Wednesday 29 November and requested all necessary assistance with the public health aspects of this incident. In addition, she formally requested all necessary co-operation with the ongoing investigation. The Russian Foreign Minister assured her that this co-operation would be forthcoming. We will contact other Governments of countries where the planes that I have mentioned might have landed in the interim.

I hope that this statement and the various bulletins issued by the health authorities have given a degree of reassurance, at least, at what is an understandably worrying time for many travellers.

I start by thanking the Home Secretary for making this statement today and for providing the Opposition with early sight of it.

We understand that more than 30,000 British Airways passengers have been alerted on the basis of risk of radiation exposure. Clearly, the grim pictures of Mr. Litvinenko in his dying days and the large number of people nominally exposed to polonium-210 traces could lead to unnecessary public alarm. I appreciate the Home Secretary’s caution on any matter involving public safety. He used the phrase—I think I have it right—“the risk of exposure is low”. Will he clarify that? In particular, will he give an objective assessment of the risk to the public, based on the expert scientific advice he has received to date, and will he confirm that this risk is very small indeed?

On Tuesday, the Prime Minister said:

“There is no diplomatic or political barrier in the way of that investigation going where it needs to go.”

Will the Home Secretary confirm that the police have been, or will be, instructed that diplomatic niceties will not obstruct or influence in any way the conduct of this investigation?

There is predictable ongoing fever-pitch speculation in the media. Will the Home Secretary provide any further answers and reassurance at this stage? I understand, particularly in the light of your comments, Mr. Speaker, that there are legal limitations to what the Home Secretary can say. However, can he quash at least one rumour reported in the press and inform the House whether any of the aircraft under inspection in London or Moscow have carried a diplomatic bag since the beginning of October this year?

Many Russian émigrés in London will be feeling alarmed about their own safety after the events of the last weeks. That alarm will have worsened after Yegor Gaidar, the former Russian Prime Minister, was taken seriously ill in Ireland and his office said that he might have been poisoned. Is any action being taken to protect and reassure other Russian dissidents in the UK?

I thank the right hon. Gentleman for his questions. As far as we can tell, the risk of exposure is very low indeed because of several factors. First, polonium-210 is an isotope that radiates over a very short distance—centimetres, rather than metres. Secondly, almost any barrier between the source of polonium-210 radiation and a person will stop the travel of that radiation—even thick paper. So if it is in a glass phial, for instance, the radiation will not travel.

Thirdly, there has to be ingestion of polonium-210, either by eating, inhalation or via a cut. As far as we are aware, with inhalation, the level in sieverts would be so low as to mean a very small risk. That is borne out by all the evidence that we have. I mentioned 29 urine tests, mainly of hospital and other staff. All have been cleared of concern, and I hope that that provides reassurance to those who may have been worried.

As for the two aeroplanes on the ground at Heathrow, one is expected to be cleared by the HPA when it has compiled its report, and the other is being monitored. Tests are being carried out and BA will make a decision on whether to bring the other aeroplane back from Moscow on the basis of the results.

As for co-operation with the Russians, my right hon. Friend the Foreign Secretary has spoken to them and we have been assured of their co-operation. We understand that that assurance goes up to the highest level in the Russian authorities. Of course, if it is necessary to use the powers that are conferred on the police to obtain access, for instance, to aeroplanes in this country, they will be prepared to exercise that power on their own judgment. There will be no political prohibition on the police following where the evidence leads them. In that context, I have no knowledge of any diplomatic bags. I had not seen that story but I will satisfy myself about the position and, if I need to correct anything that I have said to the right hon. Gentleman, I will come back and do so.

I am also grateful to the Home Secretary for his statement and advance notice of it. I have two questions, one specific and one more general. The Home Secretary referred to the need for passengers and staff on those flights to refer themselves, in the first instance, to BA and then to the health authorities. Can he confirm that procedures are in place, both for BA and NHS Direct, to refer passengers to the police if they have information of any value in identifying passengers of interest to those conducting the investigation?

Can the Home Secretary give the House an assurance that, once this episode is put behind us, the general issue of the availability and ready transport of radioactive materials will be considered with redoubled effort and the appropriate clinical priority attached? I discovered this morning that the International Atomic Energy Agency’s database on illicit trafficking has recorded more than 650 incidents since 1993 of trafficking in nuclear or other radioactive material. Those are just the incidents that the IAEA knows about, and the House will be keen to ensure that the Government will redouble their efforts to address that issue.

I thank the hon. Gentleman and he is correct that there is a BA helpline for anyone who thinks that they may have travelled on one of the planes. If necessary—and the numbers should be falling all the time—the helpline will refer them to NHS Direct, which will monitor them and refer them on if appropriate. The helpline number is 0845 6040171, and the website also has information.

The hon. Gentleman asks about cross-reference to the police. Within all the exigencies and proprieties of data protection and privacy, the agencies are liaising to refer people onwards if they have some useful information.

As regards radioactive materials, I told the House in my last statement that there are probably between 130 and 150 sites where the material might be used in some form in the UK. As far as we can make out, there has been no loss or theft from any of those sites. That is our concern in the short term, but the hon. Gentleman correctly points out that in the medium term this incident will enhance our awareness of the dangers of the proliferation of radioactive materials, and we will certainly look to learn lessons from it.

Has my right hon. Friend been advised that the radioactive footprint in the aircraft indicates polonium-210 or other radioactive material?

Of the 24 sites that have so far been investigated, contamination has been found at 12. There are two stages to the process. The first is the detection of some radioactive contamination and the second, which takes a little longer, is studying it to see which form it is. In most of the cases that I have identified, the contamination is polonium-210. It is at very low levels in some cases, and higher in others, although none is a health hazard of any significance. As my hon. Friend may know, the radiation output is measured in becquerels, which is the rate of radioactive deterioration of the material, or the number of clicks on a Geiger counter, for those who are not scientifically minded. The range of contamination of polonium-210 found so far is quite significant, but even at the higher limits it is not a huge risk to anyone.

Does not the existence of the traces on the aircraft suggest at least that that dangerous isotope can be carried on to them without being detected by all the highly sophisticated security equipment that we have at British airports at present? Is not that a loophole that the Government should look closely at closing as soon as possible?

As the right hon. and learned Gentleman says, we should try to learn all the lessons that we can from this incident. He will understand if I do not confirm or deny any technical aspects of the security precautions, but I assure him that we are concerned not only with the investigation but with what lessons we may learn from it. The willingness of the public to help in the investigation is illustrated by the fact that the staff who have been asked to help the police with their inquiries have been very helpful.

During pre-legislative scrutiny of the Civil Contingencies Act 2004, we tried to imagine the unimaginable, but we failed to imagine this event. We did think about the relationship between security, health and transport. Has my right hon. Friend yet had an opportunity to assess that relationship following this event and the response in terms of civil contingencies and emergency planning? When he has done that assessment, will he advise the House whether he is satisfied with that response?

I can tell my hon. Friend that I am happy with the co-operation that we have received from all of my colleagues in government, as witnessed by the fact that so many of them are in their places on the Front Bench. Ministers have attended Cobra regularly and worked closely together. We can learn lessons from the incident and we will have our proceedings monitored as a process, apart from the practical efforts that are in hand, so that we can see what lessons can be learned about working together.

It is believed that some of the poisoning may have taken place in various residences and other properties in my constituency. Obviously, the media have focused hitherto on the very human tragedy of this case, but I am concerned about the safety and welfare of my constituents and of those who work in and visit my constituency. I appreciate that the Home Secretary may not be able to go into great detail just now, but will he say on what basis a former senior KGB officer was given asylum in this country? Presumably, many other people from across the world are in the same boat. Should we not now give serious consideration to ensuring that people who come to this country and who intend to remain political agitators against other sovereign states are not allowed to stay?

I am not entirely sure that I agree with the hon. Gentleman.

How long does it take polonium to decay and become harmless?

It has a half life of 138 days.

Has the Home Secretary considered liaising with his counterparts in other countries to determine whether people have died under similar circumstances elsewhere? Given the international nature of the inquiries, and if there have been such deaths, would not the pooling of information be of benefit to all?

To the best of my knowledge, the only other death in similar circumstances happened back in the 1950s. However, I have no doubt that the historical and medical evidence will be reviewed as the case proceeds. At the moment, we have very little information.

NHS Direct and the Health Protection Agency have evidently been doing an excellent job in identifying, tracing and testing people. My right hon. Friend has explained what people on the relevant flights can do and how they can contact British Airways, but has he asked the airline to take proactive steps to trace people who may have been affected?

My right hon. Friend the Secretary of State for Transport has been actively involved with British Airways, which has assisted us to the best of its ability—to the extent that it has agreed, even before calls are made to NHS Direct or the health authorities, to facilitate the reception of telephone calls to confirm whether people were on particular flights. I think that the system is working satisfactorily, although I hope that people will understand the problems that arise from the sheer number of travellers involved. As I said earlier, since around 1 November the three planes that I mentioned have carried something in excess of 30,000 people to 221 destinations. However, British Airways is making every effort to respond positively in very difficult circumstances.

I welcome the Home Secretary’s statement, and thank him for giving us advance sight of it. I agree that this is a worrying time for many travellers. The right hon. Gentleman said that he was contacting the Governments of the other countries in which the planes may have landed. He specified four aircraft in his statement, but will he say whether any other aircraft or airports in the UK have been tested? Are there any plans to do so?

As far as the aircraft are concerned, I can tell the hon. Gentleman that two British Airways planes at Heathrow and one at Moscow airport are involved. In addition, an aeroplane with the Russian airline Transaero landed at Heathrow this morning, and we know of one other Russian plane in which we think that we might be interested. Other planes may be involved that we do not know about at present, but those are the five that we know of. The hon. Gentleman also asked about airports in this country. Although we believe that we need concentrate only on Heathrow, several European airports might require investigation. The investigation is dynamic and is changing by the minute, let alone the hour. If we become aware of any further problems, we will send out an immediate alert and seek to discover the whereabouts or transit of any aeroplane that might be involved.

If something like 33,000 passengers did indeed make journeys on the aeroplanes in question, it follows that several thousand would be citizens of other countries. Another possibility is that many British citizens who flew in those planes will still be on holiday or working overseas. What steps are the Government taking to ensure that other Governments and British citizens abroad are able to receive the sort of advice that NHS Direct makes available in the UK?

My right hon. Friend the Foreign Secretary and her staff at the Foreign Office are in touch with our overseas posts, and they will send out what information they consider necessary. If specific health or transport advice is needed in any particular case, they will ensure that the necessary information is supplied.

May I return to the second question asked by my right hon. Friend the shadow Home Secretary, which has not yet been answered? It had to do with the safety of political dissidents and émigrés in London and the UK. Thousands of such people have been given asylum in this country, which is seen as a safe haven for those with political views that are unpopular in their own countries. However, if dissidents and émigrés are being assassinated in public or semi-public places in London, this country will no longer be considered to be a safe haven. In my opinion, this incident has had a severely negative impact on this country’s reputation as well as Russia’s.

I find the hon. Gentleman’s final sentiment—that this incident somehow reflects badly on this country and its services—quite extraordinary. We understand that, although our traditions of liberty and free speech sometimes cause great difficulties—for the British Government, as well as for others—they are often what people come here for. It is not possible to safeguard people in this country 100 per cent., whether they are dissidents in their own countries or not. I wish that it were, but I assure the hon. Gentleman that we do our utmost to ensure that everyone who is given citizenship or asylum here is protected to the best of our ability. To cast aspersions as he has is to criticise, unduly and unfairly, our security services, police and all the many people who are trying to ensure that this remains a safe country where opinions can be stated without fear or favour. I assure him that the investigation will be carried out in that way.

My question follows on from the one asked by my hon. Friend the Member for Cities of London and Westminster (Mr. Field). Britain must remain a safe haven for people fleeing political persecution, but does the Home Secretary agree that political dissidents who become agitators can, by their actions, undermine our national security? In those circumstances, should we not have a review of the people who are allowed to stay here?

The difficulty is that the inference to be drawn from any answer to that question must be that we have already decided the outcome of the investigation. We must not get ahead of ourselves in that way. I stress that the police have not yet gone beyond saying that the death was suspicious. They will follow up all leads, some of which, as I said earlier, are changing by the hour. We are finding different sites to look at and I have no doubt that, by the time I leave the Chamber, the numbers that I have given in my statement could have changed again. We are giving the House information about this or that plane. We may discover that some, or a greater number, of the planes that we believed were of interest to us are not the right ones. That is the nature of an investigation and I urge the House to understand that while we are open as possible on such a subject—as is right, here in the cradle of democracy—we must nevertheless be responsible in using the information. However eager we are to build up a picture of conclusion in our minds, we may actually be only at the very early stages of the investigation.