Former ministers said to have been caught on camera by journalists

A group of MPs, including former ministers, have been targeted in an elaborate sting operation in which journalists set up a bogus lobbying company and offered to pay them in return for political influence.

Among the politicians approached was Stephen Byers, the former cabinet minister and arch-Blairite, who was filmed describing himself as a "bit like a sort of cab for hire". He offered to trade Westminster contacts for £3,000 to £5,000 a day.

Others who were targeted in the undercover operation included former cabinet ministers Geoff Hoon and Patricia Hewitt. Margaret Moran, the Labour MP for Luton, was also involved.

The party tried to limit the damage last night by saying some MPs were "mortified" by how stupid they had been. However, nothing illegal has been alleged.

Twenty MPs were invited to attend meetings to discuss joining an advisory board and 10 turned up. The meetings were mainly held at offices in London's St James's Square. An undercover Sunday Times journalist asked them how the company could go about influencing policy and how it could improve its chances of winning a government contract.

Byers told her he had saved hundreds of millions of pounds for National Express through his contact with Lord Adonis, the transport minister, and had influenced food labelling proposals for Tesco after phoning Lord Mandelson, the business secretary. The MP said that his friendship with Mandelson was one of his "trump cards".

However, the next day he wrote an email to the meeting's organisers saying he had "overstated" the part he had played in trying to secure changes to the way in which the government deals with issues. "This means that I have not spoken to Andrew Adonis… or Peter Mandelson about the matters I mentioned," he wrote.

Byers issued a statement last night saying that at an informal meeting about a potential job opportunity he had made some "exaggerated" claims. "Having reflected on my comments I knew that I should immediately put the record straight. I did so the following morning by making it clear that I have never lobbied ministers on behalf of commercial interests. I later withdrew my name for consideration. I have always fully disclosed my outside interests," he said. Byers described the set-up as a "massive deception".

The operation is reported to feature in a Dispatches programme to be aired tomorrow on Channel 4.

The journalists set up a lobbying company known as Anderson Perry Associates, supposedly based in the US. Its website described it as a "bespoke consultancy that helps organisations and individuals maximise and exceed expectation". It claimed to have 120 clients in Europe, the Middle East and the US, operating in the health and defence industries.

The exposé is likely to thrust the issue of standards back to the heart of the election campaign as party leaders battle to show they will clean up parliament. The operation, which targeted MPs who are standing down from parliament, also targeted the Lords, with Baroness Sally Morgan, a former aide to Tony Blair, reported to have been approached.