Read how The Sunday Times broke the story

Gordon Brown was drawn into a dispute yesterday over a claim that police secretly bugged one of his MPs during meetings with a man suspected of links to terror groups.

An inquiry was ordered into the allegation that Sadiq Khan, now a government whip, was covertly recorded during two visits he made to Babar Ahmad in the prison where he is being held. The Conservatives said that they had given warning to Mr Brown six weeks ago that an MP had been subjected to surveillance, in breach of a convention against bugging MPs, and accused him of doing nothing.

David Davis, the Shadow Home Secretary, released a copy of a letter that he said was sent to the Prime Minister on December 11 saying that he had “reason to believe” that the convention had been breached in the case of an unnamed MP, and urging a review.

But Downing Street said that Mr Brown knew nothing of such a letter. After detailed checks, a spokesman said that Mr Brown had received several recent letters from Mr Davis, including one on the Humber Bridge, but had no record of such a warning.

Government sources said it was incredible that Mr Davis appeared not to have telephoned in advance of posting such a letter, or sent a copy by fax or e-mail, nor raised such concerns with the Speaker, the Home Secretary or Mr Khan himself.

The dispute deepened the mystery surrounding claims that police used a listening device concealed in a table to record conversations between Mr Khan and Mr Ahmad when the MP visited him twice at Woodhill prison in Milton Keynes.

Mr Ahmad, a computer expert from Mr Khan’s constituency in Tooting, South London, has been detained since 2003 and is fighting extradition to the United States where he is accused of running websites to raise money and recruit fighters for the Taleban and Chechen insurgents.

Scotland Yard’s anti-terrorist police recorded Mr Ahmad’s meetings with visitors using a hidden microphone, battery, antenna and transmitter in a wooden table in the prison’s visiting hall, according to The Sunday Times.

There is no suggestion of illegality by Mr Khan, who visited Mr Ahmad in 2005 and in June 2006 in his capacity as his MP, although they are said to be friends. Mr Khan has campaigned against his extradition.

Mr Khan, a former lawyer and chairman of Liberty, who previously brought a series of high-profile cases against the Metropolitian Police, tried to calm the controversy, using a television interview to emphasise that the claim was as yet unproven and welcoming the announcement of a Government inquiry.

“We need to do whatever we can to assist the police and the security services and the important work they do, Mr Khan told the BBC’s Andrew Marr show.

“Anything that undermines the relationship between an MP and a constituent, anything that undermines the relationship between the citizen and the police and the security services obviously are serious. That’s why it’s really important that we calm down a bit.”

Jack Straw, the Justice Secretary, who ordered the inquiry, said: “Though I have no knowledge of the facts in this case, it is completely unacceptable for an interview conducted by an MP on a constituency matter, or on any other issue, to be recorded.”

But Mr Davis claimed the Prime Minister should have known of the case due to his disputed letter and said that the real question was whether the bugging of Mr Khan was sanctioned by Sir Ian Blair, the embattled Commissioner of the Metropolitan Police, or by Jacqui Smith, the Home Secretary, or by Tony Blair, who was then Prime Minister.

A Downing Street spokesperson said: “We have received a number of letters from David Davis since the beginning of December. But we have no record of receiving a letter about the bugging of MPs.”

The Wilson doctrine

— The principle that MPs should not be subjected to bugging was established more than 40 years ago by Harold Wilson

— The Wilson Doctrine, as it became known, meant that security agencies were under orders not to tap the telephones of MPs or peers. Wilson undertook to inform Parliament if that policy were to change

— All subsequent governments have upheld this doctrine, most recently Tony Blair in March 2006.

— Some interpreted it more narrowly, saying in effect it means that security agencies need the express approval of the prime minister

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