Smash hit

Replying to critics of the police action, she went on: “In my book, Stalinism and a police state happens when ministers direct and interfere with specific investigations that the police are carrying out.

“I have been very clear that in my view the police should have operational independence, they should be able to pursue those investigations in the way in which their professional judgment suggests.

“I do not know what evidence they are looking at - neither do any of the other people who are commenting.

“If you believe in the principle of operational independence of policing, you believe in that even when they are difficult and sensitive investigations.”

However, the continuity of government policy on the raid appeared to have been muddied later, when House of Commons Leader Harriet Harman said she was “very concerned” at the arrest of the Tory immigration spokesman and the way police had raided his Parliamentary and constituency bases.

There were “very big constitutional principles” that needed to be safeguarded, Ms Harman said, including the rights of MPs to get on with their job without interference from the law.

And she said Speaker Michael Martin should look at how police are able to enter the Palace of Westminster once the investigation into Home Office leaks is concluded.

Ms Harman told Sky News Sunday Live: “I think the Speaker might well want to review the processes by which authorisation is given to search the Palace of Westminster, but there was also the question of the search of his home and the constituency office.

“We have got to be sure that whilst MPs are not above the law, that actually they are able to get on with their job without unwarranted interference by the law.

"These are very, very big constitutional principles, we have to make sure they are protected.”

She added: “I think we should hold fire until after this investigation and then we can look at the complete picture and the process by which police come into the House of Commons, search an MP’s office, take the computers - which obviously raises the question of confidential privileged information between MPs and constituents - all of that sort of thing will have to be looked at.”

Earlier, David Cameron, the Tory leader, accused the Prime Minister of hypocrisy for refusing to speak out against the action.

Gordon Brown has declared simply that the decision to question Mr Green and search his home and offices was “a matter for the police” of which he had no prior knowledge.

But the Conservative leader said the now PM had “made his career from passing on Whitehall leaks...and he’ll be guilty of hypocrisy if he doesn’t speak out”.

Writing in the News of the World, he said: “When it comes to vigorous opposition, if this approach had been in place in the 1990s, then Gordon Brown would have spent most of his time under arrest.”

“The Prime Minister has simply repeated that he ’had no prior knowledge’ and this is ’a police matter’. Frankly, that’s not good enough.

“The question is: does he think it is right for an MP who has apparently done nothing to breach our national security - and everything to inform the public of information they’re entitled to know - to have his home and office searched by a dozen counter-terrorist police officers, his phone, Blackberry and computers confiscated, and to be arrested and held for nine hours?”

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