Two more former Labour ministers were secretly filmed apparently offering to use their government connections and expertise for cash, it was reported.
Adam Ingram, the former armed forces minister, and Richard Caborn, the former sports minister, were interviewed by an undercover reporter posing as a company executive wanting to hire MPs for lobbying work.
According to The Sunday Times, which carried out a joint investigation with Channel 4's Dispatches, the MPs were recorded offering their services to help commercial clients for fees of up to £2,500 a day.
However, Mr Ingram and Mr Caborn stressed they would not make themselves available for work until after the election when they are both standing down as MPs. The latest "sting" follows the suspension from the Parliamentary Labour Party of three former Cabinet ministers over allegations they were prepared to take cash to influence government policy.
Geoff Hoon, Stephen Byers and Patricia Hewitt were filmed by Dispatches discussing the possibility of working for what they thought was an American lobby firm. Labour backbencher Margaret Moran, who also featured in the programme, was also suspended.
Mr Caborn, who is standing down as the MP for Sheffield Central, was said to have expressed an interest in working for the fictitious company but said he would not decide until after the election. He was recorded discussing a number of services he could offer, quoting a rate of £2,500 "plus expenses".
"There's a number of ways in which you can influence or at least access ministers, whether it's a sector or an individual company, or what. And also on policy as well," he said.
He also claimed he would be able to get "access to ministers" and "information" if he received a peerage, according to the newspaper. Mr Caborn denied any wrongdoing and said his comments had been taken "out of context", giving the "impression of something improper going on".
He said he made it clear that he had not agreed to work for the fake firm, saying: "It would be wrong for me to commit to something that I couldn't do". A letter from the MP's solicitor to The Sunday Times said his £2,500 rate reflected three days' work.