The Tories cried "stitch-up" today after a stray e-mail revealed plans for top-level talks ahead of a statement by the Speaker Michael Martin on why police were allowed to search the Commons office of the Conservative frontbencher Damian Green

The e-mail from the office of Harriet Harman, the Leader of the House, was to organise a meeting this afternoon with civil servants and Commons officials to consider Mr Martin's much-anticipated statement to MPs, due tomorrow. It was copied to a Conservative staffer by mistake.

Those invited to the talks include Jacqui Smith, the Home Secretary, Jack Straw, the Justice Secretary Gus O’Donnell, Cabinet Secretary and Jill Pay, who as Serjeant at Arms authorised the police seach of Commons property, and Mr Martin himself. No Conservatives or representatives of any other party were invited.

Mr Green was held and questioned for nine hours last Thursday about a series of Home Office leaks. He was arrested "on suspicion of conspiring to commit misconduct in a public office and aiding and abetting, counselling or procuring misconduct in a public office".

His homes and offices, including in the Commons, were searched and his computer, phone and other communications equipment seized in the raids, which followed the earlier arrest and suspension of a junior Home Office official.

Mr Martin has been under mounting pressure from MPs on all sides to explain the police action, which many regard as a breach of Parliamentary privilege as enshrined in the 1689 Bill of Rights. As Speaker, however, he must be seen to remain above party politics.

Ms Harman’s office insisted that the advanced meeting was only to discuss the logistics of Mr Martin's statement as it will be delivered on the same day as the Queen’s Speech - although it is unclear why so many Cabinet heavyweights would be needed to settle a scheduling issue.

Dominic Grieve, the Shadow Home Secretary, said: "This is a completely improper meeting convened by the Government privately with the Commons authorities and senior civil servants to manage the Speaker’s statement without any representation from other Parliamentarians.

“This is precisely the sort of leak that should make it into the public domain. We insist on being present at this meeting along with representatives of all political parties to discuss the issues on the agenda.”

The row came after the civil servant who passed secret documents to Mr Green, the Tories’ immigration spokesman, insisted that he acted in the public interest.

Christopher Galley, 26, was arrested in a dawn raid on his home by counter-terrorist police on November 19. Mr Galley’s lawyer, Neil O’May, yesterday questioned whether the police operation was a “proportionate” response to the leaks, adding: “If there was ever a case of ’don’t shoot the messenger’, then this is it.”

Mr Green was held for nine hours, during which Tory sources say he was accused by officers of “grooming” Mr Galley and obtaining up to 20 documents.

The MP, who denies all wrongdoing and has not been charged, was released on bail to return for further questioning in February.

Gordon Brown’s spokesman has acknowledged the case raised “some difficult and very sensitive issues” and did not rule out an eventual inquiry, but urged politicians and the media not to rush to judgment before the full facts are known.

The House of Commons Public Administration Committee is also holding its own inquiry into the wider issue of the handling of leaks from Whitehall departments.

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