asked Her Majesty's Government:

What is the average cost of detaining a person under immigration laws in (a) an immigration removal centre, and (b) prison. [HL232]

The average cost of detaining a person for one night in 2005-06 was:

(a) immigration removal centre, £104; and

(b) prison, £78.

The cost provided for prison detention does not distinguish between those held under immigration laws and those held on criminal matters, as this is not discernible. Both figures reflect direct costs as per 2005-06 financial accounts.