Smith rebuked for not challenging raid police

Former minister John Reid said he was "surprised" she did not ask the police questions about their investigation leading up to the arrest and detention of the Conservative immigration spokesman. "I have to say I'm surprised you weren't informed that your opposite number, effectively, was about to be arrested," he said.

"I cannot think that if I had been told this had been done, after the event, I would have remained as placid as you have in these circumstances."

He added: "I would have wanted to have been informed and to have expressed a view on it."

His rebuke came as Ms Smith defended herself and the police in a stormy Commons session. She said she would not have intervened even if she had known an MP was to be arrested. "I believe it would have been wholly inappropriate," she said.

But shadow home secretary Dominic Grieve accused her of trying to "wash her hands" of the affair. "This episode has nothing to do with national security and everything to do with political embarrassment," he said.

With questions swirling around the case, Ms Smith indicated that more police investigations into alleged leaks are under way.

Replying to a question from ex-minister John Redwood about a stream of highly sensitive leaks from the Treasury, she said: "There have been other situations where the police have been invited to investigate by the Cabinet Office." Home Office sources confirmed other police probes had been launched.

Mr Green was arrested and held for nine hours while his Commons office, two homes and constituency office, were searched and computers removed by counter-terrorism officers seeking evidence of collusion with a leaker.

Scotland Yard faced embarrassment as it failed to deny fully breaching guidelines when it obtained consent to raid the Commons.

Ms Smith published a letter from assistant commissioner Bob Quick, who is heading the inquiry, which agreed that officers were under an obligation to inform the Serjeant at Arms Jill Pay she did not have to give consent to the search. Mr Quick, attempting to clarify the situation, said:

"The officers ... were satisfied the Serjeant at Arms understood the police had no power to search in the absence of a warrant, and therefore could only do so with her written consent or that of the Speaker."

However, Code B52 of the codes of practice says the police must be explicit. "The person must be clearly informed they are not obliged to consent," the code states.

The apparent breach by his team is a setback for Mr Quick, a contender for the job of Metropolitan Police Commissioner.

John Silverman, professor of criminal justice and media at Bedfordshire University, said the search of Mr Green's office was "unlawful" if the police did not follow procedures. "If the Serjeant at Arms was not informed of that right, the police were clearly in breach of the law and there would be repercussions from that," he told BBC radio.

Officers have been ordered to return computer equipment containing confidential files by Monday. Ms Smith told MPs that "highly classified" documents - actually a low ranking of secrecy - were leaked and there were grounds to believe greater secrets were at risk.

"The sustained level of leaking that had already taken place clearly suggested this could go on, would escalate, and that more information of greater sensitivity could potentially leak," she said.