Police who raided a Tory MP's office in Parliament failed to follow proper procedure, the Commons has heard.

Commons Speaker Michael Martin said he did not authorise the swoop on the offices of immigration spokesman Damian Green.

Mr Martin said officers did not have a warrant for last Thursday's raid and neglected to inform the Serjeant at Arms, Jill Pay, that they needed one.

The Speaker's statement came amid a furious row over the arrest of Mr Green and the searching of his offices in relation to a series of Home Office leaks.

He was held and questioned for nine hours on suspicion of "conspiring to commit misconduct in a public office and aiding and abetting, counselling or procuring misconduct in a public office" before being bailed.

Mr Green denies he broke the law by receiving leaked information from Home Office civil servant Christopher Galley.

Former Tory leader Michael Howard said MPs on all sides felt "outrage" over the arrest.

Mr Martin told a packed Commons he had been told Mr Green was about to be arrested but said: "I did not personally authorise the search. I was not told that the police did not have a warrant."

Mr Martin said Ms Pay had signed a consent form for officers to enter the precincts of Parliament but added: "The police did not explain, as they are required to do, that the Serjeant was not obliged to consent or that a warrant could have been insisted on."

Mr Martin said that a warrant will always be required in future for police to search MPs' offices.

But he added Parliamentary rulebook Erskine May makes it clear that Parliamentary privilege has never prevented the operation of the criminal law the precincts of the House should not be "a haven from the law".

Acting Scotland Yard Commissioner Sir Paul Stephenson strongly defended his force's handling of the investigation, which was launched after a complaint from the Cabinet Office.

Sir Paul said: "The police must be able to act without fear or favour in any investigation, whomsoever may be involved, where there are reasonable grounds to suspect they may have committed criminal offences.

"I would strongly refute that I or any senior officer under my command have or have allowed any improper influence of our operations or acted for political purposes. That is not what we do."

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