The prime minister made the announcement at the European political community summit in Spain after a whirlwind week at the Conservative Party conference in Manchester.

Mr Sunak urged European leaders to "unite" over migration.

Speaking to reporters, he said it had been a "very successful summit here working with other European countries to stop the boats".

"This is a shared European challenge that's very clear," he said.

"What I was able to do here for the British people is sign new deals with Serbia, Belgium and Bulgaria that will help combat the criminal gangs upstream."

While details of the deals are light, Downing Street said the deal with Belgium involved a "commitment to increase our bilateral exchange of expertise" as well using advanced detection technology to "identify and disrupt people smuggling through Belgium and onwards to the UK".

Polling reveals how well Sunak's conference speech went down - politics latest

Meanwhile the deals with Serbia and Bulgaria will focus on prosecuting and disrupting the criminal gangs and sharing intelligence.

It comes following reports in The Daily Telegraph that the UK is set to sign a deal with the EU's border agency to obtain access to the bloc's intelligence on migration.

The Telegraph reported officials in London and Brussels have concluded the substance of the agreement, which sources said is in the "final stages" and could be announced this week.

Under the deal, domestic agencies would be able to monitor the entirety of the EU's external borders rather than just shared frontiers.

Elsewhere in the interview with reporters, the prime minister addressed questions over his party conference speech, in which he touched on a range of issues including trans rights and HS2.

Mr Sunak was asked when he made the decision to scrap the northern leg to Manchester after the transport secretary, Mark Harper, said it had been made on Tuesday - despite a video emerging suggesting it was made days earlier.

He replied: "There was a Cabinet meeting on Wednesday morning and the transport secretary legally is the person who makes that decision.

"But of course, this is something that we've been working on for a while. It's right - because this is a very big decision involving tens of billions of pounds - it's not something that you do very quickly.

"The decision formally was made right at the end.

"There was that cabinet meeting on Wednesday morning, but taking a step back from the process here, what's important is the decision and I've decided that the right thing to do is to take that £36bn that would have been spent on the rest of this project and instead spend that on hundreds of projects across the entire country, which will deliver more benefit for people quicker."

During his speech Mr Sunak also drew on the issue of trans rights.

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He told the conference hall: "We shouldn't get bullied into believing that people can be any sex they want to be. They can't; a man is a man and a woman is a woman. That's just common sense."

His comments attracted some criticism, including from Green Party MP Caroline Lucas, who accused Mr Sunak of using "more nasty divisiveness from the hard right playbook".

Home Office data published today shows that transgender identity hate crimes rose by 11% from 4,262 offences to 4,732 in the year ending March 2023.

Asked whether he regretted his remarks, Mr Sunak said: "I think most people watching this programme will think that that's common sense and it's just a simple fact of biology.

"Now, of course, this is always going to be a compassionate, tolerant country - but we can't ignore fundamental facts of biology and saying those things shouldn't be controversial."