MPs want action to be taken over the treatment meted out to Mr Green
The inquiry into alleged leaks of Home Office documents which led to MP Damian Green being arrested is "continuing", a Scotland Yard source has told the BBC.
The source said the investigation was "moving on quite quickly" and there there were no plans to drop it.
Senior Tories are furious that police held Mr Green, the shadow immigration minister, for nine hours last week.
Downing Street said it would judge the "full facts" before deciding whether an inquiry should be held into the case.
Mr Green was arrested on Thursday on suspicion of conspiring to commit misconduct in a public office, but not charged.
The Ashford MP, who denies any wrongdoing, was held while his homes and offices were searched.
House of Commons Speaker Michael Martin - under pressure to justify why he allowed police to enter Parliament and search Mr Green's office - is due to address MPs on Wednesday.
When police questioned the MP, 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.
BBC political editor Nick Robinson said he had been told that Conservative frontbenchers had had legal advice "on the difference between merely receiving a leak" and "inducing leakers to leak".
A spokesman for Prime Minister Gordon Brown said the arrest of Mr Green had raised "difficult and sensitive issues".
Downing Street has not ruled out an inquiry into the issues surrounding the case, although MPs have been urged not to rush to judgement and await the outcome of the police investigation.
WHAT IS THE LAW?
The police arrested Mr Green on suspicion of "conspiring to commit misconduct in a public office" and "aiding and abetting, counselling or procuring misconduct in a public office".
Mr Brown's spokesman said: "There may well be a time when it is right to look at the issues arising from this case."
Earlier, Justice Secretary Jack Straw told BBC Radio 4's Today programme: "Everybody who has been made aware of these unfolding events, of course, is surprised by the nature of the raid.
"I certainly understand the concern of my parliamentary colleagues."
But he added: "We don't have a police state here, despite many of the ridiculous newspaper headlines. A police state would be where ministers were directing an investigation...
"We have an independent police service."
On Sunday Home Secretary Jacqui Smith told the BBC she had not known in advance about the raids and refused to apologise, saying it would have been "Stalinist" had she interfered in the investigation into Home Office leaks.
Mr Straw told Today: "If an investigation is an investigation of your own department, then there are still more reasons why the home secretary needs to stand back from it.
"If any home secretary had offered an apology, there would then be a huge furore about the home secretary prejudicing the investigation."
'Out of control'
For the Conservatives, shadow home secretary Dominic Grieve told BBC Radio 4's The World at One that Ms Smith's comments had been "quite astonishing".
He said: "All this suggests a situation that is completely out of control, chaotic, and the consequence is that a Member of Parliament has been really ruthlessly prevented from discharging his job."
The information leaks had been "massively in the public interest" because they dealt with "cover-ups" of the government's "own incompetence", Mr Grieve said.
The civil servant at the heart of the leaking allegations, 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 is Tory anger over what they say was the police's use of the controversial term "groomed" because it is usually used in relation to child sex offences.
Home Secretary Jacqui Smith and Justice Secretary Jack Straw speak to the press
MPs from all the main parties have denounced Mr Green's treatment, saying they believe the raids on his Commons offices amounted to an attack on their ability to represent constituents and hold the government to account.
The Daily Telegraph reports that some politicians are threatening to disrupt the state opening of Parliament on Wednesday in protest, with senior Conservatives considering organising a walk-out unless the authorities apologise.
Leader of the Commons Harriet Harman said she thought there should be a review of the rules in such cases and of how it was possible for the authorities to allow the raid on Mr Green's Commons office to take place.
Any review should take place after the police inquiry ends, she said.
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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