A review of the arrest of the Tory frontbencher Damian Green has raised concerns about the way police conducted the investigation, it emerged last night.
The report by Ian Johnston, the chief constable of the British Transport Police, questioned the actions of officers and whether the inquiry "met current policy and best practice", the man in charge of the leak investigation revealed.
The Conservatives immediately condemned "serious failings" in the inquiry, as senior MPs demanded that Mr Johnston's review be published in full. Mr Green, the shadow Immigration minister, was arrested and questioned for nine hours last month in connection with a string of leaks from the Home Office. Police also raided his Commons and constituency offices, provoking uproar from MPs of all political parties.
There has been growing speculation that police will drop their investigation into Mr Green. Last night, Assistant Commissioner Bob Quick, the Metropolitan Police officer in charge of the inquiry, said he would not publish the review while the case was ongoing, but confirmed that it had found the arrest of Mr Green to be lawful. He said: "[Mr Johnston] recognises that there are arguments, either way, regarding proportionality over the manner of arrest of a Member of Parliament but questions the method taken in this case."
A Conservative Party spokesman said: "We believe Damian Green has done nothing wrong. This statement shows that there were very serious failings in the police operation."
Andrew Mackinlay, the Labour MP for Thurrock, said: "Clearly, it is acutely embarrassing. [The police] are hiding behind the excuse of 'ongoing criminal proceedings' to hide that embarrassment."