Ex-foreign secretaries Jack Straw and Sir Malcolm Rifkind have been cleared of breaking lobbying rules after an undercover TV investigation.
The two had denied wrong-doing after discussing possible future work with Dispatches programme reporters posing as staff of a fake Chinese firm.
Parliament's standards commissioner said neither broke Commons rules.
But Channel 4 is standing by its story and has asked broadcasting watchdog Ofcom to investigate the programme.
A Channel 4 spokesman said: "This programme raised important questions which concern voters about how senior politicians are able to use their public office for personal financial gain. This is a matter of public interest and was a legitimate journalistic investigation.
"We're confident in our journalism and have decided to take the unprecedented step of inviting our statutory regulator Ofcom to investigate it.
"Full transcripts of the interviews are in the public domain and we are in the process of making the programme available on All4, our online platform, to enable people to make up their own minds."
The programme was a joint investigation with the Daily Telegraph. In a statement the newspaper said: "The Daily Telegraph conducted an investigation that was in the public interest and accurately revealed matters which were of concern to millions of voters.
"We raised a number of serious questions about the conduct of Members of Parliament. We suspect voters will find it remarkable that, despite the scandal of MPs' expenses, Parliament still sees fit for MPs to be both judge and jury on their own conduct."
Prime Minister David Cameron welcomed the standards commissioner's report clearing Sir Malcolm.
A Downing Street spokesman said: "After a long and distinguished career in the House of Commons, the prime minister welcomes the fact that that Sir Malcolm, and his family, can now put this distressing episode behind them".
The two then-MPs were secretly filmed by reporters claiming to represent a Hong Kong-based communications agency called PMR which was seeking to hire senior British politicians to join its advisory board.
Sir Malcolm was said to have claimed that he could arrange "useful access" to every British ambassador in the world because of his status, while Mr Straw boasted of operating "under the radar" to use his influence to change European Union rules on behalf of a commodity firm which paid him £60,000 a year.
Parliament's standards commissioner Kathryn Hudson said there had been "errors of judgement" from Sir Malcolm while Mr Straw had breached the code of conduct "by a minor misuse of parliamentary resources".
She was critical of the sting carried out by Channel 4's Dispatches and the Daily Telegraph.
She wrote: "If in their coverage of this story, the reporters for Dispatches and the Daily Telegraph had accurately reported what was said by the two members in their interviews, and measured their words against the rules of the House, it would have been possible to avoid the damage that has been done to the lives of two individuals and those around them, and to the reputation of the House."
Kevin Barron, chairman of the standards committee of MPs, which oversees breaches of Commons rules, said: "Everything Jack Straw and Malcolm Rifkind said about their earnings was already published online in the register of members' interests.
"What was said in the interviews should have been reported accurately and measured against the rules of the House. Jack Straw and Sir Malcolm Rifkind were presumed guilty before any authoritative investigation had taken place."
Sir Malcolm said: "Channel 4 Dispatches and the Daily Telegraph must recognise the judgment of the Standards Commissioner and the Standards Committee that they were responsible for 'distortion' and for misleading the public in making these allegations.
"It has been for me, for my family and for my former parliamentary staff a painful period which we can now put behind us. My public life has continued over the last seven months with the support of colleagues. I am looking forward to the years ahead in very good spirits."
Mr Straw, who had been widely tipped to be elevated to the House of Lords before the programme was broadcast, said: "Throughout my 36 years' parliamentary career I took great care to act with probity and to treat the rules of the House of Commons with the greatest respect. I am most grateful to the Committee on Standards for confirming this.
"They say that I had been 'particularly at pains to keep his business work separate from his Parliamentary resources', and that I had 'made declarations even when such declarations were not technically required'.
"It has been very sad that the final chapter of my long period in the Commons has been overshadowed in this way. The whole episode has taken a huge toll on my family, my friends, and on me, but the commissioner's conclusions and the committee's findings will now enable me to get on with my life."