A senior police officer has been appointed by Acting Metropolitan Police Commissioner Sir Paul Stephenson to review the handling of the police inquiry into Home Office leaks, Scotland Yard announced today.

A senior police officer has been appointed by Acting Metropolitan Police Commissioner Sir Paul Stephenson to review the handling of the police inquiry into Home Office leaks, Scotland Yard announced today.

Sir Paul has asked British Transport Police Chief Constable Ian Johnston to report to him within seven days.

In the meantime, the investigation team - who last week arrested Conservative immigration spokesman Damian Green - will consult with the Crown Prosecution Service about further steps in the inquiry.

Mr Johnston, who is chairman of the Association of Chief Police Officers crime committee, has been asked to look into the Metropolitan Police's "decisions, actions and handling of the investigation", said Sir Paul.

The decision to call him in reflects concern at Scotland Yard over the political furore which has blown up over Mr Green's arrest on suspicion of conspiring to commit misconduct in a public office. The Ashford MP denies all wrongdoing and has been released on bail until February.

His arrest provoked a furious response from London Mayor Boris Johnson, the chairman of the Metropolitan Police Authority and other senior politicians, including Conservative leader David Cameron, who described it as "heavy-handed".

MPs have questioned the decision to conduct a police search of Mr Green's House of Commons offices, which some regard as a breach of parliamentary privilege.

In a statement released by Scotland Yard this morning, Sir Paul said: "I am properly concerned about the issues being raised within the continuing debate surrounding the ongoing investigation into the leaking of Government information.

"I have therefore appointed Ian Johnston, chairman of the Acpo crime committee and the Chief Constable of British Transport Police, to conduct an urgent review of our decisions, actions and handling of the investigation to date and to provide me with an interim report within seven days and a further report within two weeks.

"In the meantime, the investigation team will be meeting the CPS to review progress and consider next steps."

Home Secretary Jacqui Smith welcomed Mr Johnston's appointment and revealed that she sought assurances from Sir Paul yesterday that the inquiry was being carried out in a "proportionate" manner.

In a statement, she said: "I welcome Sir Paul's appointment of Chief Constable Ian Johnston to conduct a review of the Metropolitan Police Service's decisions, actions and handling to date of the ongoing investigation into the leaking of Government information.

"In view of the gravity and sensitivity of this ongoing investigation, I spoke to Sir Paul yesterday to seek his assurance that the investigation was being pursued diligently, sensitively and in a proportionate manner. Sir Paul informed me of his intention to conduct a review of the handling of the case, which I welcomed.

"I reiterated my support for the police's operational independence from political interference.

"No-one should seek to prejudice a police investigation in any way. These are very serious matters, and the police should be free to pursue their investigations without fear or favour."

Boris Johnson also welcomed Mr Johnston's appointment: "I welcome Sir Paul Stephenson's sensible appointment of Ian Johnston to lead a thorough review of the handling of the investigation and arrest of Damien Green MP.

"It is right that someone independent should look closely at how the police conducted this investigation and whether the actions and decisions they took were proportionate and necessary and I am pleased at the common sense approach this represents."

Conservative sources have described the arrest of Mr Green, who was held for nine hours while his homes and offices were searched by anti-terror police, as "Stalinesque" and suggested that it must have been ordered or authorised by senior ministers.

But both Ms Smith and Prime Minister Gordon Brown have insisted that they had no prior warning of Mr Green's arrest and said that the police investigation must be allowed to run its course.

Acpo president Ken Jones - himself a contender, alongside Sir Paul, for the job of Metropolitan Police Commissioner - last night defended the Met's actions.

"If an investigation reveals that any person may be involved in wrongdoing then they have the right to expect that we will investigate the matter in ways which seek to get at the truth and either sustain the allegation or exonerate them. No one can be above the law," said Mr Jones.

Senior Conservatives were today meeting to consider their approach to tomorrow's showdown with Commons Speaker Michael Martin, who is due to deliver a statement to MPs on the police search of Mr Green's office in the Palace of Westminster.

Many MPs are furious at the police raid, which they regard as a breach of parliamentary privilege.

Mr Martin is expected to reveal whether he personally authorised police to enter the Palace, and what role was played by the Serjeant at Arms Jill Pay and the Clerk of the Commons Malcolm Jack.

It is thought Conservatives may raise points of order in the hope of forcing a debate on the floor of the Commons, potentially disrupting arrangements for the State Opening of the new parliamentary session and the Queen's Speech.

Tories were today demanding to be allowed to take part in a top-level meeting of ministers, civil servants and Commons officials about Mr Martin's statement.

A leaked email revealed that Harriet Harman, the Leader of the House, is organising the meeting about "arrangements of the Queen's Speech and considerations in advance of the Speaker's Statement on Police Action and Parliament".

Those invited included Ms Smith, Justice Secretary Jack Straw, Cabinet Secretary Sir Gus O'Donnell and the Serjeant at Arms, but no Conservatives.

Ms Harman's office insisted that the advance meeting was only to discuss the logistics of the event, as the statement will be on the same day as the Queen's Speech. The contents of the statement itself was "entirely a matter for the Speaker", said a spokesman.

But shadow home secretary Dominic Grieve 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.

"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 Christopher Galley, the civil servant who passed secret documents to Mr Green, insisted yesterday that he acted in the public interest.

Mr Galley, 26, was held for 17 hours after being arrested in a dawn raid on his home by anti-terrorism officers on November 19. He has been released on bail until January.

His 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."