Andy Burnham has said he is prepared to publicly disagree with US President Donald Trump when Britain's national interests demand it, in his first major broadcast interview since becoming prime minister.

Speaking exclusively to the BBC, Burnham said he would always put Britain first and would not hesitate to challenge the US president "if right for Britain". Asked directly whether he would call out Trump if required, the prime minister replied: "Of course."

The remarks, contained in excerpts released on Sunday ahead of a full interview to air on the BBC's Panorama programme on Monday, offer the clearest sign yet of how the new prime minister intends to manage the transatlantic relationship. They come days after the two leaders held what both described as a warm first telephone conversation, and against the backdrop of previously strained UK-US relations under Burnham's predecessor, Sir Keir Starmer.

"All leaders have to do that. You have to defend your own national interest before anything else," Burnham told the BBC's Laura Kuenssberg. "That's what you're required to do if you're to do this job properly."

He added: "I can't at any point say that I won't take a different opinion from him, that I will need to voice a different idea that is right for Britain."

The comments set out an early marker for how Burnham, who became prime minister only last Monday, plans to balance cooperation with Washington against the pressures of domestic and international policy. The warmth of the leaders' first exchange stands in sharp contrast to Trump's earlier public language about Burnham, whom he had dismissed as "the mayor of a town" and described as "extremely liberal".

Burnham singled out the US conflict with Iran as an area of particular "concern", confirming he would speak his mind on what he believed to be appropriate. On defence, he said he was "absolutely committed" to what had been promised to NATO partners, though he acknowledged that work remained on how to fund it.

"The first challenge facing us both is to ensure that the defence investment plan is fully funded, and that's the thing that's right in front of us, and we need to work that through as we go towards the budget later this year," he said.

The funding question carries added significance because Burnham's new chancellor, John Healey, resigned as defence secretary in the previous government after warning that Britain would not be safe unless it committed to spending 3% of GDP on defence by 2030. Pressed on the target, Burnham said work still needed to be done on how to pay for it.

"I appointed my new chancellor very aware of what he had said about the critical importance of defence spending and the position that he had taken about that," Burnham said.

The prime minister also used the interview to rule out an early general election, committing to the next scheduled poll in 2029. "I'm going to rule it out. Yeah, there's no early general election. I don't think people want it," he said.

The two leaders spoke by telephone on 20 July, the day Burnham took office. In a post on his Truth Social platform after the call, Trump said Burnham "has got a big job ahead of him, but he will be able to do it" and pledged that the US "will be there to help". He added: "The call was interesting, and went very well. I wished Prime Minister Burnham, GOOD LUCK AND GODSPEED!"

Trump said the conversation had touched on four issues: North Sea oil, trade, the military alliance and the demining of the Strait of Hormuz. The two men have agreed to meet in person "in the not too distant future", though no date has been set.

Burnham's rise to Downing Street has been swift. The 56-year-old left Westminster in 2017 to become mayor of Greater Manchester, where he earned the nickname "King of the North" for his outspoken defence of northern England during the Covid-19 pandemic. He returned to Parliament only weeks ago, winning the Makerfield seat, before running unopposed to succeed Starmer. He was announced as Labour leader on 17 July at the Trades Union Congress in London and became prime minister three days later in a transition of power presided over by King Charles.

He is the United Kingdom's 59th prime minister and its seventh in a decade.

Starmer announced on 22 June that he would step down after less than two years in office, his premiership having come under mounting pressure following a series of controversies, a poor performance in the 2026 local elections and a run of cabinet resignations. Leaving No 10, his parting line was: "My work is done."

Starmer had endured a fraught relationship with Trump, who had criticised him over differences on the US-Israeli conflict with Iran, immigration, energy and technology regulation.

Since taking office, Burnham has reshaped his top team, appointing allies including Healey to the Treasury. Reporting on the precise allocation of cabinet portfolios has varied between outlets. On Friday, he formally opened a newly created northern office at Heron House in Manchester, promising "a different way of" governing.

The new prime minister has faced some criticism for not conducting major interviews or press conferences since taking over from Starmer. He also faces questions over how he will reconcile his defence commitments with a series of domestic pledges, including removing VAT from energy bills, cutting 20% from pub and club business rates, and capping bus fares at £2.

The full interview will be broadcast on Panorama on Monday.