Conservative former ministers Matt Hancock and Kwasi Kwarteng told a fake overseas company looking for MP advisers that their daily rate for consultancy would be £10,000 ($12,000).
In a sting set up by campaign group Led By Donkeys, Mr Hancock and Mr Kwarteng both set out the sums for what they would expect to be paid to advise a non-existent firm in South Korea.
There is no accusation of wrongdoing, with MPs permitted to seek employment outside of parliament.
Mr Hancock, asked whether he had a daily rate during an online “interview”, said: “I do, yes. It is 10,000 sterling.”
The former health secretary, who was stripped of the party whip by Prime Minister Rishi Sunak after he was announced as a contestant in last year’s series of ITV reality programme I’m A Celebrity … Get Me Out Of Here!, later said he had an hourly rate of “around £1,500”.
A spokesman for Mr Hancock said the West Suffolk MP had “acted entirely properly and within the rules”.
Former Tory chancellor Mr Kwarteng, when asked the same question, said: “I would say as an MP, obviously I don’t need to earn a king’s ransom.
“But I wouldn’t do anything less than for about $10,000 a month.”
Mr Kwarteng, whose mini-budget in September sent the value of the pound tumbling and mortgage rates soaring, went on to clarify that he would prefer the rate to be in pounds.
Told by a fake employee of the company they were considering offering between £8,000 and £12,000 per day, with the intention for him to attend six board meetings a year, Mr Kwarteng said: “OK yes, we’re not a million miles off. We can work with the numbers.”
Labour accused Tory MPs of using “their taxpayer-funded offices to line their own pockets”, calling the behaviour “shameful”.
Cabinet minister Michael Gove on Sunday came out in defence of Mr Hancock and Mr Kwarteng, arguing they had acted “within the rules”.
“When Members of Parliament do work that complements the work they do in the House of Commons, then it is absolutely vital that we know who is paying them, what they earn and that is what the register [of MPs’ interests] is there for,” the Levelling Up Secretary told Sky News.
“On this occasion, I think it is pretty clear that things that were offered and considered were within the rules,” he added.
“But inevitably all of us will reflect on this and think the first duty of a Member of Parliament is towards their constituents.
“And ultimately, the really important thing is, is an MP delivering for their constituents, is a Member of Parliament doing everything they can to put public service first?”
Led By Donkeys, an anti-Brexit group, said it created a sham company called Hanseong Consulting, setting up a website and paying for a so-called “fake virtual office” in the South Korean capital Seoul.
It said, after consulting the register of MPs’ interests, it approached 20 MPs from different parties asking if they would join the phoney firm’s international advisory board.
The group sold the “company” as one with aims to expand into the UK and Europe, asking any would-be advisers to attend pretend board meetings held in a mix of locations, including allegedly in South Korea.
According to its preview video posted on social media, Led By Donkeys said 16 of the MPs approached were Tory, two Labour, one a Liberal Democrat and the other an independent.
Out of those contacted, five are said to have progressed to an online interview stage, including Mr Hancock and four Tories: Mr Kwarteng, former education secretary Gavin Williamson, former minister Stephen Hammond and Graham Brady, chairman of the 1922 Committee, an influential back bench body.
Mr Brady, according to the video, said he was “thinking something like £60,000 as an annual rate” for assisting the firm.
The senior Tory said he made clear to those behind the hoax that any work would have to fall “within the terms of the Code of Conduct”.
Led By Donkeys said Mr Wiliamson had turned down the opportunity to take discussions any further.
MPs are permitted to have second jobs on top of their role representing constituents.
But external employment opportunities for those in Westminster have come under the spotlight in recent years, following former Tory cabinet minister Owen Paterson’s suspension from the Commons for breaching lobbying rules in 2021.
He later quit parliament following a furore after Boris Johnson’s administration attempted to abolish the standards body that dished out the punishment.
All five MPs who held a so-called “interview” with the campaigners have been approached for comment.
A representative of Mr Hancock said: “The accusation appears to be that Matt acted entirely properly and within the rules, which had just been unanimously adopted by parliament.
“It’s completely untrue to suggest any wrongdoing and therefore absurd to bring Mr Hancock into this story through the illegal publication of a private conversation.
“All the video shows is Matt acting completely properly.”
Mr Brady said: “Having decided to leave the Commons at the next election, I have received a number of approaches regarding future opportunities.
“I did have an exploratory discussion with someone purporting to be recruiting an international advisory board for a South Korean investment house.
“I made it clear that any arrangement would have to be completely transparent and that while a Member of Parliament, I would only act within the terms of the Code of Conduct.
“I also made it clear that while I could be flexible in attending international meetings in person, this would be subject to some important votes or commitments in Westminster.”
