MPs want action to be taken over the treatment meted out to Mr Green
Senior Tories are furious that police who arrested MP Damian Green accused him of "grooming" a Home Office mole to leak him information.
This latest revelation comes amid reports angry MPs may disrupt the state opening of Parliament on Wednesday.
On the same day, Commons Speaker Michael Martin will address Parliament about the raid on Mr Green's offices.
Meanwhile, many MPs are reported to be dissatisfied with Home Secretary Jacqui Smith's response so far to the arrest.
When police questioned Mr Green - the shadow immigration minister - they are said to have suggested to him that he had not "simply received leaked" information but "groomed" a civil servant who had allegedly passed him 20 confidential documents.
The man, who has been named in newspapers, was a Conservative activist who is believed to have previously applied for jobs in Mr Green's office.
There was Tory anger over the police's use of the controversial term "groomed" because it is usually used in relation to child sex offences.
The important principle is that MPs - apart from when they're speaking in the chamber and dealing with constituents' correspondence - are as subject to the same laws as the rest of us
The Speaker of the House of Commons, Michael Martin, is also under pressure to justify why he had allowed police to enter Parliament and search Mr Green's office.
His office has said he will address MPs on Wednesday.
Tory MP Ed Vaizey said the arrest had been an "outrage".
He said: "The idea of the police arresting an MP and searching his office, I think, crosses a very important line - particularly on the nature of the investigation, which was to do with receiving documents from a government department which this government department would rather this MP had not done."
Former Labour minister Denis MacShane told the BBC's Today programme that Mr Martin should apologise to MPs for allowing police to search Mr Green's office.
"What I want him to say is that on reflection what happened should not have happened," Mr MacShane said.
"The inner sanctum, if I can call it that, of our parliamentary democracy is the Palace of Westminster.
"The police, the agents of the state, do not storm in there and start breaking in, going into offices and taking away files that all our constituents think will be treated confidentially."
However, constitutional expert Vernon Bogdanor of Oxford University said the row was a "storm in a teacup".
"The important principle is that MPs - apart from when they're speaking in the chamber and dealing with constituents' correspondence - are as subject to the same laws as the rest of us," he added.
Ms Smith has refused to apologise for Mr Green's arrest and on Sunday told the BBC's Andrew Marr programme it would have been "Stalinist" for her to intervene in a police investigation.
Pressed by Andrew Marr about what she knew when, Ms Smith said she had known there was a leak inquiry going on and knew in advance that a Home Office official was being arrested as part of it on 11 November.
Jacqui Smith challenged over Damian Green's arrest
She has maintained there was no ministerial involvement in the investigation and said she only knew about Mr Green's arrest after it happened.
The prime minister has always insisted that ministers, including the home secretary, had no "prior knowledge" of the arrest.
But Leader of the Commons Harriet Harman has said she "understands" the anger amongst MPs and said she thought there should be a review of the rules in such cases and how it was possible for the authorities to allow the raid on Mr Green's Commons office to take place.
"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," she said, adding that she believed any review should take place after the police inquiry ends.
"These are very, very big constitutional principles, we have to make sure they are protected."
The chairman of the commons public administration committee, Tony Wright, has said he will set up an inquiry into how these matters should be handled in the future.
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