Two peers, including a former cabinet minister, were suspended from the Labour Party on Sunday after being filmed apparently offering to use their power and influence in Parliament for cash.

Lord Cunningham, who served in Tony Blair’s government as Agriculture minister, and the former senior police officer Lord Mackenzie of Framwellgate were recorded by undercover reporters posing as lobbyists seemingly boasting at how they get round House of Lords rules to promote their client’s interests.

For £144,000 a year Lord Cunningham claimed to be able to offer to arrange parliamentary questions on behalf of a fictitious solar energy company, arrange company events in the House of Lords and lobby ministers on the firm’s behalf. A third peer, Lord Laird, resigned the Ulster Unionist Party whip after being targeted by the same investigation.

It comes just two days after the Tory MP Patrick Mercer resigned the whip after being filmed by Panorama apparently offering to use his parliamentary privileges to lobby on behalf of Fiji.

The revelations will increase the pressure on David Cameron finally to follow through on his manifesto pledge to clean up the UK’s lobbying industry and introduce a mechanism for MPs to be kicked out of the House of Commons.

In a statement, Labour said the peers had been suspended “pending further investigation”. “The Labour Party expects the highest standards of its representatives and believes they have a duty to be transparent and accountable at all times,” the party said.

All three peers deny breaching the rules and have referred themselves to the House of Lords Commissioner for Standards.

Lord Cunningham, a privy counsellor who led the joint committee on Lords reform under Tony Blair, asked for a fee to provide a lobbying service. He told the reporters, who were posing as representatives of a South Korean solar energy company, he would become their advocate at Westminster. Lord Cunningham said he offered “value for money” because he could introduce them to senior figures in all three parties.

“Introductions and getting to see people, including the ministers – this is part of the package,” he said.

He would be happy to ask questions in the Lords and could “get other people to ask questions as well”. He could also host receptions on the terrace for the reporters and their fake client.

But on Sunday he said he had been using the meeting to test his suspicions that he was being targeted by a scam. “I quickly became suspicious of them and the money they were offering. What the [Sunday Times] article does not make clear is that I told the undercover journalists I always stick to the rules and declare any interests. The article also fails properly to acknowledge the fact I informed them the next day I wanted nothing more to do with them.”

Lord Mackenzie described navigating parliamentary lobbying rules as “walking on eggshells”, but denied any wrongdoing. “I’m very meticulous about what I do and what I don’t do and make sure that I’m not crossing the boundary. When I left that interview, I checked the code of conduct in the House of Lords and I came to the decision that it was very near the mark and I immediately emailed the people who did the interviewing and I said that I’m not interested.”

The Cabinet Office Minister Francis Maude said both the recent Lords and Commons scandals underlined the need for legislative action. He said it was “very unlikely” the Government would go into the next election without a statutory register in place, and attributed the delay in implementing it to “sorting out the final details”.

Peer pressure: Lords under investigation

Lord Cunningham

Rose through the unions, joining the shadow Cabinet in 1983. Agriculture Minister from 1997, then Minister for the Cabinet Office. Led a joint committee on Lords reform under Tony Blair. Created Baron Cunningham of Felling in 2005. Allegedly offered to introduce reporters to senior figures for £12,000 a month. Denies any wrongdoing but has been suspended pending an investigation.

Lord Mackenzie of Framwellgate

Rose through police force to president of Police Superintendents’ Association, then law-and-order adviser to Tony Blair. Introduced the idea of a sex offenders’ register. Was made a peer in 1998. Allegedly offered to ask questions and host events for paying clients. Denies the allegations. Has been suspended by Labour pending investigation.

Lord Laird

Became the youngest member of Northern Ireland parliament in 1970, winning by-election prompted by the death of his father. Entered the Lords in 1999. Claimed he could swap questions with other Lords and offered to set up an all-party parliamentary group to push reporters’ interests. Denies allegations but has resigned the Ulster Unionist party whip.