Britain will pay France nearly half a billion pounds over the next three years to step up efforts to prevent small boats from crossing the Channel.
Prime Minister Rishi Sunak committed to sending Paris £478 million (€541m) to fund a new package that will include hundreds of French law enforcement officers and a new detention centre established in France.
Mr Sunak announced the package after meeting French President Emmanuel Macron during a UK-France summit at the Elysee Palace in Paris.
But there was no sign of the returns agreement with France that the British government desires as Mr Sunak makes "stopping the boats" one of his top priorities.
The UK has already committed more than £300 million to France in the last decade to help tackle unauthorised migration.
More than 3,000 people have already made the perilous sea journey this year, with almost 46,000 arriving by unofficial routes in 2022.
That is despite Mr Sunak and Home Secretary Suella Braverman announcing a £63 million package to increase patrol officers by 40% four months ago.
That package followed a £55 million deal in 2021.
'Best possible relations'
President Macron said he wants France to have the "best possible relations" with the UK but that they need to "fix" the consequences of Brexit.
Following today's talks in Paris with Rishi Sunak, the French leader hailed a "new beginning" in the Anglo-French relationship following the turbulence of recent years.
While he welcomed Mr Sunak's Windsor Framework agreement with Brussels on trading arrangements with Northern Ireland, he also made clear there was still unfinished business from the UK's departure from the EU.
"On the short front we have to fix the consequences of the Brexit. Probably some of those consequences were underestimated but we have to fix them," he told a joint news conference at the Elysee Palace.
"What we want to do now is build new partnerships on defence and security, on facing the war (in Ukraine), regarding climate change, in order to co-ordinate our international activity. And for our businesses and our people we want to build new links, new relations.
"My wish, definitely, because it makes sense with our history, our geography, our DNA, I would say, is to have the best possible relations and the closest alliance.
"But it will depend on our commitment, our willingness, but I am sure we will do it."
The meeting marked the first Anglo-French summit in five years, after relations between the two countries soured under Boris Johnson, with the French leader making clear he did not trust the former prime minister.
Mr Macron seemed particularly pleased at a commitment to facilitate school visits between the two countries.
Mr Sunak said: "I always say, we left the EU but we didn't leave Europe. Emmanuel said previously 'Brexit didn't change geography'.
"We want to have a close, co-operative, collaborative relationship with our European partners and allies. And of course, that starts with our nearest neighbour, France, and today is the first step on that journey.
"We're writing a new chapter in this relationship, and I'm really looking forward to everything that we can build on in the coming months and years ahead."
