In order to increase attempts to stop tiny boats from crossing the Channel, Britain will grant France about half a billion pounds over the next three years.
Rishi Sunak has promised to transfer Paris £541 million, or £478 million, to pay for the new package.
Many French law enforcement officials will be hired as part of it, and a new detention facility will be built there.
Following his meeting with French President Emmanuel Macron at the UK-France summit on Friday at the Elysee Palace in Paris, Mr. Sunak made the announcement about the package.
But there was no sign of the returns agreement with France that the Government desires as Mr Sunak makes ‘stopping the boats’ one of his top priorities.
Mr Sunak was speaking in Paris following the announcement of the Illegal Migration Bill, which has already faced backlash from various charities.
It will stop those arriving from claiming asylum, seeking citizenship or returning to the UK in the future.
The Bill will push ‘the boundaries of international law’, Home Secretary Suella Braverman had told reporters.
The legislation is likely to get a rough ride in the Lords, as the upper chamber considers whether to amend the legislation.
If the Government does not accept the changes, then a lengthy back and forth could delay the implementation.
In the House of Commons, Ms Braverman had said: ‘The need for reform is obvious and urgent.’
She added: ‘They will not stop coming here until the world knows that if you enter Britain illegally you will be detained and swiftly removed.’
The plans have been criticised by refugee groups, who say they are unworkable and will only make the system more costly and chaotic.
Patrick Ryan, Chief Executive of leading modern slavery charity Hestia, said today: ‘We need to be tougher on the organised criminals who are exploiting vulnerable people, not on the victims.’
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 Ms Braverman announcing a £63 million package to increase patrol officers by 40% four months ago.
That package followed a £55 million deal in 2021.