The inquiry into the bugging of a terrorist prisoner and his MP has been asked to examine whether the eavesdropping was carried out at the request of the FBI.

The Times has learnt that two weeks after the taped conversation with Sadiq Khan, MP, in June 2006, Babar Ahmad was visited in Woodhill jail by Metropolitan Police Special Branch detectives who told him: “We could help you if you will help us.”

Lawyers for Mr Ahmad, 33, who is fighting extradition to the United States, believe the approach was an attempt to persuade him to negotiate a plea-bargain deal before a trial in the US on terror charges.

Mr Ahmad was arrested in London in 2004 on a US extradition warrant over his alleged involvement with websites said to be recruiting for Taleban and Chechen Mujahidin groups.

Searches of his home and office at Imperial College London, where he was an IT technician, were carried out by the Metropolitan Police and material was passed to the US authorities. “Why were they scratching around when the decision had been made a long time ago that Babar Ahmad was not going to be prosecuted in Britain?” asked Gareth Peirce, Mr Ahmad’s solicitor. “Were they trying to exploit some perceived vulnerability in the bugged conversation?”

Ms Peirce said she has written to Jack Straw, the Justice Secretary, and Jacqui Smith, the Home Secretary, raising issues she wants the inquiry into the bugging to look at. She said: “Very serious questions have to be asked about who this eavesdropping was being carried out for.”

Mark Kearney, a former police intelligence officer at the prison in Milton Keynes, has claimed he was put under pressure by the Met to carry out the bugging. Mr Kearney, 48, is being prosecuted for allegedly leaking unrelated information to a local newspaper journalist. The former officer wants to give evidence to the inquiry into the bugging incident but has yet to hear from Sir Christopher Rose, the Chief Surveillance Commissioner, who is conducting it.

Times Recommends

• Deal struck to rescue Jodrell Bank
• S&M madam: Nazi claims are rubbish
• Operation Goodnight: holiday town curfew