Boris Johnson will face a showdown with his own backbenchers over plans to ban MPs from paid political consultancy work.

MPs will vote on new rules to curb their outside business interests amid a fresh row over alleged Tory “dirty tricks” and Westminster “sleaze”.

In a surprise initiative, the Prime Minister announced that he supported a ban on consultancy ahead of a vote on the issue called by Sir Keir Starmer on Wednesday.

The Government effectively took over Labour’s opposition day debate by tabling an amendment with its own proposals.

The move provoked a furious response from Labour who accused ministers of “watering down” their original motion, effectively making it non-binding.

And the move also risks further inflaming tensions between the Prime Minister and his backbenchers.

Mr Johnson will face the backbench 1922 Committee later on Wednesday in a bid to repair relations with his MPs.

Sir Geoffrey Clifton-Brown, treasurer of the 1922 Committee, said there was “dissatisfaction” with the Prime Minister in the Tory ranks.

He told BBC’s Today programme that he had “no problem” with a ban on paid consultancy work but going further could “deter a whole class of people” from entering politics.

“I think we all need to take a long, deep breath on this and get it right,” he said.

“There are two real aspects to it. One is how we represent our constituents. And the second is what sort of type of people we want in Parliament.

“Because if we ban all second jobs, I think you are going to deter a whole class of people who represent the business opportunities in this country.”

Relations between Mr Johnson and his MPs have been strained by the Owen Paterson furore, when Tories were ordered to support a move to block the former minister’s immediate suspension for breaking lobbying rules only for the Government to U-turn in the face of a furious backlash.

Sir Geoffrey said: “There is dissatisfaction on the back benches and that is why the Prime Minister needs to make it very clear to members of Parliament what he expects from us.”

Labour’s proposal calls for a ban on “any paid work to provide services as a parliamentary strategist, adviser or consultant”.

Crucially, it also includes provisions requiring the Commons Standards Committee to come forward with proposals to implement the ban and guaranteeing time on the floor of the House for MPs to debate and vote on them.

In contrast, the more vaguely worded Government amendment simply describes the consultancy ban as “the basis of a viable approach” and supports the work of the Standards Committee to update the MPs’ code of conduct.

Shadow Commons leader Thangam Debbonaire said it was “typical Tory dirty tricks” and an attempt to water down the proposals.

Cabinet minister Anne-Marie Trevelyan suggested that MPs could reasonably work up to 20 hours a week on a second job.

The International Trade Secretary told the BBC: “I think there is a common-sense test which is if you probably do 40-50 hours a week doing your main job, doing 10 or 15 hours a week doing something else, whatever you choose to do in your spare time, whether that’s paid or not paid, is something that is part of the richness of what you bring as an individual to your role as an MP.”

She later revised that figure up, telling Today: “Let’s say two shifts, that would be 16 hours a week. Are we saying 10 to 20 hours a week outside your work as an MP and a parliamentarian? If that’s what you chose to do as your choice, that’s fine.”

Ahead of his potentially awkward meeting with the 1922 Committee, Mr Johnson will face his usual session of Prime Minister’s Questions in the Commons before being grilled by senior MPs on the Liaison Committee.

In a further sign of concern at standards in politics, a second Labour motion will attempt to force the Government to release minutes of meetings between ministers, officials and Randox.

Randox is the diagnostics company which employed Mr Paterson, the former cabinet minister who triggered the storm, as a consultant.

And there is fresh scrutiny of the role of all-party parliamentary groups (APPGs) and the firms which provide support for them.

The Commons Committee on Standards launched an investigation into the groups in late 2020 and the BBC reported that an estimated £30 million has been poured into APPGs over the past five years.

The BBC investigation found that of that total, an estimated £6.4 million was donated by companies registered as lobbyists.

Tory MP Michael Fabricant said he welcomed the inquiry into the groups as “some are thought to receive large sums of money from foreign governments and companies”.