Three members of the House of Lords allegedly offered to use their influence for personal gain in a widening scandal over lobbyists paying legislators.
A series of media sting operations has thrust the lobbying issue into the limelight and already forced a lower house lawmaker, Patrick Mercer, to resign from the ruling Conservative Party and seek legal advice.
The three House of Lords peers caught out by undercover reporters from The Sunday Times newspaper are Jack Cunningham and Brian Mackenzie of the Labour Party and John Laird of the Ulster Unionist Party.
All three deny breaking the chamber's rules.
Laird resigned from the Ulster Unionists pending an investigation. The Labour Party said it would consider disciplinary action against any of its peers found to have broken the Lords code of conduct.
The trio were covertly filmed offering to ask parliamentary questions, lobby ministers and host events in prestigious House of Lords premises in exchange for payment from whom they were told were lobbyists acting for companies.
The scandal will renew pressure on Prime Minister David Cameron to introduce a statutory register of lobbyists, as promised in 2010 in the coalition agreement between his Conservatives and their junior partners, the Liberal Democrats.
Cameron warned more than three years ago that lobbying was "the next big scandal waiting to happen" but critics, including some Liberal Democrats, accuse him of dragging his feet.
Sunday Times reporters approached Cunningham, a former minister under then prime minister Tony Blair in the 1990s, pretending to represent a South Korean solar energy company.
"Are you suggesting £10,000 a month? Make that ... £12,000 a month. I think we could do a deal on that," he was quoted as saying during a discussion about his fees for what was described as consultancy work.
Cunningham later denied any wrongdoing, saying he had referred to "a fanciful £12,000 a month" to test his suspicion that he was talking to undercover journalists.
There was also footage of the other two peers caught in the sting, Mackenzie and Laird.
Mercer was caught out by undercover reporters from The Daily Telegraph and the BBC's investigative Panorama programme posing as lobbyists for businesses seeking to end Fiji's suspension from the Commonwealth on human rights grounds.
Mercer tabled five questions to government and a parliamentary motion on the Fiji issue after being paid £4,000 (HK$47,000) as part of a bogus contract he believed would earn him £24,000 a year, the two media reported.
He told the fake lobbyists he had persuaded 18 other members of parliament to join an all-party group on Fiji, commenting that they included "several freeloaders that would like to go to Fiji" and one who asked to take his wife.