Conservative MP Patrick Mercer has resigned the party whip after being caught up in a lobbying scandal and will quit parliament at the next election.
In a statement issued on Friday afternoon, Mercer said BBC Panorama was planning to broadcast allegations he had broken parliamentary rules.
I am taking legal advice about these allegations, and I have referred myself to the Parliamentary Commissioner for Standards," he said.
"In the meantime, to save my Party embarrassment, I have resigned the Conservative Whip and have so informed Sir George Young. I have also decided not to stand at the next General Election."
A Conservative Party spokesman said: "The prime minister is aware. He thinks Patrick Mercer has done the right thing in referring himself to the Parliamentary Commissioner for Standards and resigning the whip. It's important that the due processes take their course."
The BBC said it has been "investigating lobbying and the conduct of MPs and members of the House of Lords" including Mercer.
"The programme is still being made and will be broadcast as soon as possible. The investigation has raised a number of issues related to those involved. Panorama has sought responses from a number of people including Mr Mercer."
Mercer is a harsh critic of David Cameron and was infamously reported to have described the prime minister as "an arse". The Newark MP was sacked from the Tory frontbench in March 2007 after suggesting it was ok to call soldiers "black bastard” and that some ethnic minorities were "idle and useless".
It has been reported that Mercer fell victim to reporters posing as a lobbying firm who allegedly paid him to lobby on behalf of Fiji.
The Daily Telegraph conducted the investigation with the BBC and the broadsheet's editor Tony Gallagher said the details, due to be published tomorrow, are "shocking".
Mercer has tabled two written parliamentary questions on Fiji in the past month. On May 20 he asked the Foreign Secretary "what assessment he has made of the UK's investment in public transport in Fiji". And on May 16 he asked a four-pronged question about Fiji's human rights record and its status in the Commonwealth.
Before becoming prime minister David Cameron said lobbying was "the next big scandal waiting to happen".
"It's an issue that crosses party lines and has tainted our politics for too long, an issue that exposes the far-too-cosy relationship between politics, government, business and money," he said.
However Cameron has come under fire for failing to introduce tighter regulation on lobbying firms as promised in the coalition agreement.
In 2011 Liam Fox resigned as defence secretary after being accused of giving improper access to the Ministry of Defence to a lobbyist friend. And in 2010 several former Labour ministers were stripped of their parliamentary passes after being caught by undercover reporters offering to use their access to make money as lobbyists.