Rishi Sunak is braced for a Commons showdown over his flagship Rwanda plan, as allies sought to play down the damaging prospect of two Tory deputy chairmen joining a backbench rebellion.

The Prime Minister is under pressure from both sides of his party over the legislation aimed at reviving the stalled plan to deport some asylum seekers to the east African nation.

He is battling to quell Tory dissent as the Safety of Rwanda Bill returns to the House of Commons on Tuesday for six hours of debate and voting.

In a move that will deepen the Tory split, former prime minister Boris Johnson gave his support to more than 60 right-wing MPs backing amendments to beef up the flagship legislation.

But any attempt by Mr Sunak to placate them would be opposed by more moderate Tories, who want to ensure international law is respected.

It comes as the United Nations High Commissioner for Refugees said that, even unamended, the Bill and recently signed treaty with Kigali would still violate global refugee law.

The infighting heated up on Monday evening when senior Conservatives Lee Anderson and Brendan Clarke-Smith said they would back the right-wing changes.

The amendments aim to disapply international law from the Bill and severely limit individual asylum seekers’ ability to appeal against being put on a flight to Kigali.

They were tabled by Robert Jenrick, who resigned as immigration minister over the legislation, and veteran Tory Sir Bill Cash.

Tory deputy chairman Mr Anderson tweeted: “I have signed the Cash & Jenrick amendments. I will vote for them.”

Mr Clarke-Smith, who was only appointed to the same job seven weeks ago, wrote: “I want this legislation to be as strong as possible and therefore I will be supporting the Jenrick/Cash amendments.”

While the deputy chairmanship is not a Government role, holders would be expected to back its positions.

Mr Sunak will have to consider sacking them from their party posts.

Former prime minister Mr Johnson, while no longer an MP, is still an influential voice in the Tory circles – particularly with Mr Sunak’s critics.

He said: “This Bill must be as legally robust as possible – and the right course is to adopt the amendments.”

Touring broadcast studios on Tuesday, Cabinet ministers Michael Gove and Mel Stride sought to play down Tory divisions.

Levelling Up Secretary Mr Gove said he was “pretty sure” Mr Anderson would still be in post at the next election.

“I think we might be getting ahead of ourselves because I think that, and Lee is a friend and I’m a big admirer of his, the concerns that Lee has about the Bill are the concerns that the country has about migration more broadly,” he told Times Radio.

Work and Pensions Secretary Mr Stride declined to be drawn on whether the Tory deputy chairmen could face the sack.

He told LBC: “We all know that there are very few Bills – very, very few Bills – that go through straight and clean and nobody tries to amend them in any way at all.

“What matters is that the Bill progresses in a form that leaves it effective at the end and I’m confident we’re going to do that.”

Former home secretary Dame Priti Patel, who first signed a UK migrants deal with Rwanda in April 2022, gave her backing to Mr Sunak’s legislation but said it should “go further” so that “all potential roadblocks are removed, including the civil service blob” by making clear that the “civil service code cannot be used by officials to obstruct decisions”.

Dame Priti said measures should be taken to ensure that, should ministers use the Bill to ignore so-called Rule 39 orders, injunctions from the European Court of Human Rights in Strasbourg that have previously been used to block flights to Rwanda, then civil servants must comply with the decision.

In an article for The Sun newspaper, she wrote: “The Rwanda Bill gives ministers the power to decide whether to comply with Rule 39 and the Government must force the civil service to let them use it to ensure our robust plans to tackle illegal migration can be operationalised.”

In a last-ditch attempt to calm hardliners’ concerns, the Prime Minister will draft in around 150 judges and free up courtrooms in order to deal with migrant appeals.

The Prime Minister’s official spokesman said that while the Rwanda Bill would ensure the bar for legal challenges is “set extremely high”, it is “also right to ensure that we have the resources to deal with the minority of claims should they arise”.

Miriam Cates, another prominent right-wing MP, said she would also be prepared to vote against the Bill if it was unamended, and also appeared unmoved by the Prime Minister’s latest plan.

She told BBC Radio 4’s Today programme: “Well, I’m afraid all that shows is that the Government is expecting a large number of individual claims.

“We’re not saying that people should not be able to make legal claims. What we’re saying is that those claims need to be made in Rwanda.”

Tory MP Sir Simon Clarke echoed those concerns in a post on social media, saying: “This proves the extent of the problem the Bill as drafted will create – 150 badly needed judges and courts snowed under with a profusion of claims against removal.”

Jane Stevenson, a parliamentary private secretary in the Department for Business and Trade, is also said to be supporting the amendments.

If they are selected, the amendments are unlikely to pass as they will not get Labour support, but the real test will come at the third reading on Wednesday when rebels may vote against the entire Bill.

On the eve of the parliamentary battle, Tory political strategist Isaac Levido warned feuding MPs at the 1922 backbench committee that “divided parties fail”.

Mr Sunak on Monday sought to woo the right as he signalled there are circumstances where he would be prepared to ignore Rule 39 orders.

But rebels dismissed the claim, with right-winger Sir John Hayes saying Mr Sunak’s verbal promise was not enough and needed to be “backed up by legal provisions”.

The Prime Minister has previously argued that moving a further “inch” on the Bill, to more explicitly breach Britain’s obligations under international law, would risk the Rwandan government quitting the deal.

If the rebels are successful, blocking Mr Sunak’s flagship Bill would trigger fresh chaos, which might make opponents toe the line to let it pass.

Meanwhile, centrist Tories warned that any caving to the right wing’s demands would “cause problems” for them.

The Government’s Bill and a treaty with Rwanda are intended to make the scheme legally watertight following a Supreme Court ruling against the plan.

Mr Sunak won a key Commons vote on the legislation in December despite speculation about a major rebellion by Tory MPs then.

Even if it clears the Commons this week, it will face an uphill battle in the Lords.