I have been asked to reply.
As a matter of longstanding policy and practice the UK will neither confirm nor deny the existence of any extradition request made or received by this country ahead of arrest pursuant to the extradition request.
Two Russian citizens have been arrested whose extradition has been requested by the Russian Federation and their cases are currently under consideration. Neither of the subjects of the requests has British citizenship. Because the applications are under consideration, no responses have yet been given.