Three former Labour ministers face being barred from Parliament after being rebuked for breaching lobbying rules.
The Standards and Privileges Committee ordered ex-defence secretary Geoff Hoon to apologise and said his Commons pass should be suspended for five years.
Former transport secretary Stephen Byers, who likened himself to a "taxi for hire" in a sting by undercover reporters, committed a "particularly serious breach" and should have access rights restricted for two years.
Ex-sports minister Richard Caborn was also ordered to say sorry and faces a six-month suspension.
The cross-party committee cleared ex-health Secretary Patricia Hewitt of breaching the Code of Conduct, but found she was "unwise" to agree to meet what she thought were representatives from a lobbying firm.
Another former minister, Adam Ingram, and Tory Sir John Butterfill were also cleared of wrongdoing but criticised for bad judgment.
All the individuals involved stepped down from parliament at the general election, but retain Westminster passes as ex-MPs.
The House authorities launched a probe last spring after a sting operation by reporters for Channel 4's Dispatches and the Sunday Times.
Mr Byers was caught on film describing himself as a "cab for hire", requesting £5,000-a-day and boasting how he had secured secret deals with ministers over a rail franchise contract and food labelling on behalf of private companies. The then North Tyneside MP's claims were flatly denied by the Labour government, and he later apologised.
Ms Hewitt and Mr Hoon were filmed suggesting they would charge £3,000 a day for their services.
Mr Caborn, who is standing down as the MP for Sheffield Central, was said to have expressed an interest in working for the fictitious company but said he would not decide until after the election.
He was recorded discussing a number of services he could offer, quoting a rate of £2,500 "plus expenses".
Mr Ingram, whose constituency was East Kilbride, reportedly said he could cultivate a network of former ministers and could use his contacts to help the fake company develop a relationship with serving ministers and civil servants.
Mr Ingram said he was paid £1,500 a day or £1,000 a meeting by firms.
The comments in the recordings were condemned by politicians from across the political spectrum, and the Labour party suspended those involved.
The sleaze inquiry concluded that Mr Byers' remark about being a "taxi for hire" was "clumsy and ill-judged", but did not break the code of conduct. He had also properly registered payments for work outside parliament.
However, his claim to have access to confidential information from Downing Street was untrue, and he lied about the food labelling amendment and the rail franchise contract, as well as about working for Rio Tinto, and contacting civil servants on behalf of water companies.
This action had brought the House "into disrepute", the probe found.
The committee said: "We recommend that, for committing a particularly serious breach of the Code of Conduct, Mr Stephen Byers' entitlement to a Parliamentary photopass be suspended for two years, with effect from 1 January 2011. If Mr Byers had not accepted that his conduct was wrong and had not apologised in such unequivocal terms, we would have recommended that this entitlement be withdrawn for a much longer period."
In a statement today, Mr Byers said: "I am obviously pleased that after a full investigation the Parliamentary Standards Commissioner has found that I did not abuse my position as a Member of Parliament and specifically that I did not lobby the Government on behalf of commercial organisations and that I fully declared my outside interests.
"I have always accepted that I should not have spoken in the terms I did, which is why at the time I took immediate steps to withdraw my comments."
The cross-party committee said it understood that people leaving parliament wanted to "provide for a secure future".
"But we are still surprised that experienced MPs fell for it," the report added. "They should have known better. Their behaviour raises serious questions about their judgment."
Mr Hoon has argued that he was not covered by the Code of Conduct because he had been discussing work he might do after stepping down as member for Ashfield.
However, the watchdog rejected this suggestion and found he had brought the House into disrepute by claiming he had "inside knowledge" of the pending Strategic Defence Review.
"In our view, Mr Hoon was giving a clear impression during these exchanges that he was offering to brief clients about the strategic defence review on the basis of a confidential briefing he had received from Ministry of Defence officials," the committee said.
"We recommend that for committing breaches of the Code of Conduct, one of which was a particularly serious breach, Mr Geoff Hoon apologise to the House through this Committee in writing and that his entitlement to a Parliamentary photopass be suspended for five years, with effect from January 1, 2011."
The committee ruled that Mr Caborn had failed to declare financial interests properly when discussing health restructuring, and when booking House of Commons facilities.
Those breaches were "comparatively limited" and more likely to have been by "oversight" rather than "intention".
"We recommend that for breaching the Code of Conduct Mr Richard Caborn apologise to the House through this Committee in writing and that his entitlement to a Parliamentary photopass be suspended for six months, with effect from January 1 2011," the watchdog added.
In a statement today, Mr Caborn said: "This is a total vindication, after a 10-month inquiry, that clears my name and reputation after 31 years in public office and I thank the Commissioner and his staff for carrying out a thorough investigation."
The MPs said that although she was "unwise", Ms Hewitt made only "minor" errors in her contacts with the fake lobbyists that did not amount to a breach of the rules.
Sir John, who represented Bournemouth West, made comments about his potential elevation to the House of Lords that were "clearly unwise" and "reflected poorly on him", but were not outside the code.
Mr Ingram was also cleared of wrongdoing, but had been "unwise" to agree to meeting the reporters, according to the report.
The photopass suspensions will need to be rubber-stamped by the House before being implemented.
The committee said a wider review into Parliament's lobbying restrictions was needed, including tightening rules on MPs advocating causes that would benefit organisations or individuals paying them.
Contacts between ex-MPs and their former colleagues who are still in the Commons should also be looked at, as should contacts with officials.
"We agree with the (Standards Commissioner John Lyon) that there is a strong case for a review of the rules relating to lobbying. Such a review could consider the three specific points identified above, which have arisen from his inquiry into the conduct of six former members.
"We intend that such a review will be carried out as soon as time permits."
Commons leader Sir George Young said the Commons would decide next Wednesday whether to enforce the sanctions against the MPs.
Responding to a question from Conservative Greg Hands (Chelsea and Fulham) about what could be done to ensure there was no repetition of the scandal, Sir George added: "I very much hope that report (of the Standards and Privileges Committee) will act as a salutary lesson to anybody thinking of repeating these offences that were made in those cases."Reuse content