A new Anglo-French deal to stop migrants crossing is “not the end of the story”, Rishi Sunak said on Friday as he prepared to sign a three-year agreement with Emmanuel Macron worth a potential £200 million.

The Prime Minister was speaking as he travelled by Eurostar to a summit with the French President in Paris for talks on the small boats crisis, post-Brexit arrangements, defence and Ukraine.

Describing the meeting as the opening of a new chapter in Anglo-French relations, he said he would not be signing a small boats deal unless the money was spent on officers, surveillance equipment and other infrastructure that would “make a difference”.

The Prime Minister warned that there was no silver bullet to solve migrants crossing the Channel, which have seen more than 3,000 reach the UK so far this year. Home Office projections suggest the number of migrants making the crossing by the end of 2023 could be as high as 80,000.

The new deal to be agreed at the Elysee Palace later on Friday is expected to provide as much as £70m a year to pay for more officers, surveillance equipment and “upstream” investigations to smash the people smuggling gangs and supply routes. It follows a £63m agreement signed last November.

Mr Sunak told reporters on the Eurostar to Paris: “The more that I’ve spent looking at this problem, the more time and energy I’ve devoted to it, the more convinced I am that we can grip the problem.

“And I’m going to throw absolutely everything we can at doing so.

“The new [Illegal Migration Bill] this week was a big part of that but I’ve always said that increasing cooperation with our French allies is a part of it as well. And it won’t finish today either.

“November was a start. Hopefully we can go and build on that today and I’m sure that won’t be the end of the story either. This will be a continued partnership.”

Britain has given France more than £250m in successive deals since 2015 but migrant numbers have continued to rise to a record 45,000 last year, up from 28,000 in 2021.

The French have increased the proportion of migrants being stopped on the beaches from 40 per cent to more than 50 per cent, preventing 3,000 leaving so far this year. However, UK Border Force chiefs believe it needs to be raised to 80 or 90 per cent if the smugglers’ business model is to be broken.

There are also concerns at French tactics which do not see migrants arrested. Under French law, it is not an offence to try to board a boat to leave France, which means they are released to make more attempts.

Mr Sunak said: “If we are investing money we want to make sure that it is going on things that we think will make a difference. So you would always expect me to do that, and that’s why we would not invest any money alongside the French in a joint endeavour unless we thought it was going to go on things that will make a difference.

“The only other thing I would say as I always say about these things is that there is no one silver bullet to solve this problem.

“So the legislation we introduced this week is incredibly important. Cooperation with the French is important. Illegal migration enforcement at home is important.

“Returns agreements are important with countries like Albania, so there are lots of things that we need to do. There is no one silver bullet.”

Mr Sunak said it was also a “sensible investment” to stop the migrants at source.

“Everyone knows that we are spending five and a half million pounds a day plus on hotels. We would rather not do that, and the best way to stop that is to stop people coming in the first place,”  he added.

The Prime Minister is expected to press President Macron to help Britain secure an EU-wide agreement for migrants who arrive illegally in Britain to be returned to the EU.

Post Brexit, just 21 migrants have been returned to EU countries and none of those were returned to France.