Justice Secretary Jack Straw ordered an immediate inquiry on Sunday into allegations that Scotland Yard anti-terrorist police secretly bugged an MP during private conversations with a constituent in prison.

The Sunday Times reported that Sadiq Khan, a government whip and Labour MP for Tooting, was bugged twice while meeting the constituent, who was in prison awaiting deportation to the United States to face terrorism charges.

The electronic listening device was hidden in a table at Woodhill prison in Milton Keynes and picked up conversations between the two in 2005 and 2006 about the latest developments in the U.S. extradition request, the newspaper said.

Police have been forbidden to eavesdrop on politicians since a bugging scandal involving Labour Prime Minister Harold Wilson's government.

"I have ordered an immediate inquiry into this matter," Straw said in a statement. "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."

Muslim groups in Britain reacted with anger to the reports.

"Today's revelations are simply appalling and raise a whole range of vital issues to do with confidentiality and how to hold to account the improper behaviour of senior police officers," Dr. Muhammad Abdul Bari, secretary-general of the Muslim Council of Britain, said in a statement.

"This kind of behaviour cannot but do immense damage to the level of trust between Muslim communities and the police."

Hizb ut-Tahrir, an organisation Britain threatened to ban after the 2005 attacks on London, said the allegation was a sign of increasingly draconian security measures.

"Is it any surprise that many Muslims believe Britain is becoming a police state for our community?" it said in a statement.

Conservative home affairs spokesman David Davis said he had alerted Prime Minister Gordon Brown to the bugging incident last year but had not received a reply. He had not named the MP in the letter dated December 11, 2007.

Downing Street said it had no record of the letter despite a detailed check.

Khan, a former human rights lawyer and parliamentary private secretary to Straw, welcomed the inquiry. "They are at the moment just allegations," he told BBC1's Andrew Marr show.

"I'm obviously keen ... to find out whether the allegations are true because the implications are clearly quite serious."

He said the meetings were ordinary and routine.

Khan's constituent, Babar Ahmad, is accused of running Web sites supporting terrorism and raising funds for Muslim militants in Chechnya and Afghanistan, and with urging Muslims to fight a 'holy war.'

He has not been charged in Britain with any offence.

The Sunday Times said it had seen a document which showed there was concern within Scotland Yard over the bugging, which went ahead regardless.

Scotland Yard said it was not prepared to discuss the allegation.