The Prime Minister said that Britain needs the Iron Lady’s resolve to stop enemies using “migration as a weapon” by deliberately driving people to our shores to “destabilise” society.

In a major speech in Rome yesterday, he said he is ready to push for an overhaul of international asylum rules if that is what it takes to break the business model of people-smuggling gangs.

He warned that if illegal migration is not tackled it will shake people’s faith in “our very systems of government”.

At the annual gathering of the Brothers of Italy, the country’s largest political party, he referred to Mrs Thatcher three times as he strived to convince Right-wing Conservatives at home that he is not weak on migration.

And after talks with Prime Minister Giorgia Meloni, who leads the Brothers of Italy, Britain and Italy will now jointly finance a scheme to return migrants in Tunisia to their home countries.

Number 10 said that after the talks Mr Sunak and Ms Meloni had agreed to co-fund a project that would see the two countries “promote and assist the voluntary return” of migrants currently stuck in Tunisia. Many migrants from African states cross from Tunisia to Europe.

A Downing Street spokesperson said: “They also agreed to deepen UK-Italy co-operation on security and economic development across North Africa.”

Mr Sunak wants his party to get behind emergency legislation to ensure the Government will not be stopped from sending asylum seekers to Rwanda for processing.

Mr Sunak had told his Italian audience: “Margaret Thatcher never shied away from the hard choices and the big issues.

“And today, there is no issue to which we need to apply Thatcher’s radicalism and drive to more than illegal migration.”

Warning of the backlash if the issue is not tackled, he said: “It will overwhelm our countries, and our capacity to help those who need our help most.

“The cost of accom- modating these people will anger our citizens, who won’t understand why their money should be spent on dealing with the consequences of this evil trade.

“It will destroy the public’s faith not just in us as politicians, but in our very systems of government.”

In what will be seen as a clear message to critics in his own party who say his Bill to save the Rwanda scheme – struck down by the Supreme Court last month – does not go far enough, he said that Lady Thatcher “understood that ideas only mattered if you could implement them”.

But he signalled he is prepared to take controversial action to stop ­people smuggling, saying: “If that requires us to update our laws and lead an international conversation to amend the post-war frameworks around asylum, then we must do that. Because if we don’t fix this problem now, the boats will keep coming and more lives will be lost at sea.”

Mr Sunak received a warm welcome from close ally Ms Meloni. But he faces a political storm when his Rwanda Bill returns to the Commons in the New Year.

One of the most senior MPs at the heart of efforts to get the PM to tighten up the plan issued a stern warning, saying: “This Bill needs major surgery. We cannot afford to see another small boats law enacted and then fail just months out from an election.

“It will mean total annihilation at the ballot box, even worse than we are facing.”

Mr Sunak has resisted calls to pull out of the European Con-vention on Human Rights – a move that would enrage centrist Tories. But the senior MP insisted the ECHR must not be allowed to stop flights taking off. They said: “The Prime Minister seems more worried about his reputation on the international stage than solving this for the British public.

“We all know we have to respond to our constituents’ concerns. We cannot allow Strasbourg to block flights again and we must close off routes to individual legal challenges.

“We all hope he can come back and meaningfully strengthen this Bill. We can’t have anything else.”

But one of the most senior members of the One Nation Group of moderate Conservatives warned against agreeing to changes demanded by the Right.

“We can accept the Bill as it is, just about, but we would not be able to accept it if it is amended in the way some of our colleagues want,” they said.

Exclusive polling by WeThink shows fewer than one in five people (19 per cent) believe Mr. Sunak will be able to unite the Tories in time for the election expected next year.

Nearly six out of 10 (58 per cent) do not think he can bring the different factions together.

The research also shows 67 per cent of voters expect the small boat crisis to continue over next summer, with only 13 per cent thinking it will be over by then.

Mr Sunak’s Rwanda legislation cleared its first hurdle last week when MPs on the Tory Right chose to abstain in an early vote rather than oppose it. The Bill went on to the next stage in the parliamentary process with a majority of 44.

But the European Research Group of MPs warned that as it stands it is an “incomplete solution to the problem of legal challenges in the UK courts” that would require “very significant amendments”.

Sir John Hayes, the chairman of the Right-leaning Common Sense Group of Tory MPs, said that the efforts to tighten up the Bill are “a constructive process, not a destructive one”.

Arguing that Mr Sunak wants to “get planes flying and get boats off the Channel,” he said: “It’s the Prime Minister who set out his objective – we’re looking to help him achieve it.”

A Government source said: “The PM will carry on talking to lots of MPs in the coming weeks.

“If there are any suggestions of how to make the legislation more effective, that has a credible legal argument and wouldn’t collapse the Rwandan scheme, he of course would be open to that.

“We are confident this is a very strong piece of legislation – most legal experts, former judges, say it is effective and it will work.

“Labour voted against all legislation to tackle illegal migration – the question is, why don’t they want to stop the boats?”

On Friday, 292 people crossed in seven vessels. It was confirmed a migrant died and another was left in a critical condition during an incident on the same day.

Shadow immigration minister Stephen Kinnock said: “After a week in which the Prime Minister has failed to convince many of his own backbenchers that he has a workable plan to end dangerous boat crossings, we hit a new grim milestone. Far from stopping the boats, on Rishi Sunak’s watch this year 600 boats have crossed.”