An investigation is to be launched after claims Tooting's MP was bugged while visiting a constituent in prison.

According to the Sunday Times Labour MP Sadiq Khan's conversations with Babar Ahmad in Woodhill Prison, Milton Keynes were recorded on two occasions.

Mr Ahmad - although facing no charges in the UK - is in jail awaiting a decision from European courts to see if he will be extradited to the US on suspicion of running websites raising cash for the Taliban.

It is claimed the secret recordings were made by Scotland Yard's anti-terrorist branch using a hollowed-out table in the prison's visiting hall.

The Met had previously bugged members of Mr Barbar's family who were leading the campaign to free him.

Justice Secretary Jack Straw has ordered an inquiry into the claims saying it would be completely unacceptable for an MP to have been recorded in this manner.

Government rules bar police and other agencies from eavesdropping on MPs and there was no suspicion of criminal conduct by Mr Khan to justify the operation.

The MP is said to be furious over the claims and told The Sunday Times: "From what you have told me, this is an infringement of a citizen's right to have a private meeting with his MP,"

Speaking on BBC One's Andrew Marr Show, Mr Khan said: "Clearly I'm concerned, and that's why I'm pleased that the Secretary of State for Justice Jack Straw - as soon as he heard about these allegations yesterday - has ordered an inquiry. "

Mr Khan, 37, has been friends with Mr Ahmad since they were children and campaigned for his release.

The Met has said it will not comment on the claims.