Rishi Sunak insisted his new plan to revive the stalled Rwanda asylum scheme “blocks every single reason that has ever been used to prevent flights”.

As the Prime Minister battled to keep his Tory party behind him, he claimed going any further would mean “the entire scheme will collapse”.

Mr Sunak has staked his reputation on coming up with a plan to “stop the boats” but his authority has been damaged by the resignation of immigration minister Robert Jenrick, who claimed the plan does not go far enough.

At a Downing Street press conference he said the Government’s proposed new immigration law would “restore people’s trust that the system is fair”.

The Prime Minister said: “Today the Government has introduced the toughest anti-illegal immigration law ever.

“I know that it will upset some people and you will hear a lot of criticism about it, so it’s right to explain why I have done this.”

Mr Jenrick resigned on Wednesday over the new emergency legislation aimed at reviving the policy by declaring Rwanda a safe country after the scheme to send asylum seekers there was ruled unlawful by the Supreme Court.

Former home secretary Suella Braverman also said the law did not go far enough, saying it would need to override international conventions in order to succeed.

But Mr Sunak said the Safety of Rwanda Bill “blocks every single reason that has ever been used to prevent flights to Rwanda from taking off”.

“The only extremely narrow exception will be if you can prove with credible and compelling evidence that you specifically have a real and imminent risk of serious and irreversible harm,” he said.

He said that failing to recognise that would “undermine the treaty” signed with Rwanda.

The Kigali government has stressed the need for the new UK legislation to be compatible with international law.

Mr Sunak said: “If we go any further the entire scheme will collapse and there is no point having a Bill with nowhere to send people to.”