King Charles's visit to the US next week could 'absolutely' help to repair the country's fractured relationship with the UK, Donald Trump has claimed.

The King and Queen will travel to Washington on Monday for a four-day trip to mark the 250th anniversary of the US declaration of independence as the monarch looks to shore up the special relationship.

Charles will hold a private meeting with the US President and deliver a speech to Congress before visiting New York, Virginia and Bermuda.

The UK-US relationship has plunged to its lowest point in decades as Keir Starmer refuses to unquestionably support Trump's war against Iran.

But asked if the trip could repair relations, Trump told the BBC: 'Absolutely. He's fantastic. He's a fantastic man. Absolutely the answer is yes.

'I know him well, I've known him for years. He's a brave man, and he's a great man. They would absolutely be a positive.'

Trump has repeatedly lashed out at Sir Keir, calling the UK's approach to the Iran war 'terrible' and mocking him for being 'no Winston Churchill'. 

In another swipe he suggested 'we don't want another Neville Chamberlain', who is remembered for the policy of appeasement towards Nazi Germany before World War Two. 

But Trump said he believed the PM could 'recover' if he changes his migration policies.

He added: 'If he opened the North Sea and if his immigration policies became strong, which right now they're not, he can recover, but if he doesn't, I don't think he has a chance.'

The president has consistently intervened in British politics and on Monday said Lord Mandelson's appointment as Ambassador to the US was a 'really bad pick'. 

Sir Keir has tried to play down his frayed relations with Trump. Last week he told Parliament the special relationship is 'far greater than anyone who occupies any particular office at any particular time'. 

Trump, meanwhile, has called King a 'wonderful person', and insisted he is distinct from the diplomatic drama.

When the pair sit down together next week, it will first be for a private tea hours after Charles touches down, and then another meeting behind closed doors in the White House the next day, without any media present.

Charles's address to Congress, only the second by a British monarch, will be broadcast to American television, when he is expected to speak of the 'challenges' the UK and US face.

Both he and Trump will also read prepared speeches at the extravagant White House State Dinner.

There will also be a visit to New York to commemorate the victims of 9/11.

Earlier this month Trump gushed over the King, calling him a 'great gentleman, a friend of mine' and a 'fantastic person'.

When asked which aspect of the state visit he was looking forward to most, Trump said: 'Just being with him. I've known him for a long time. He's wonderful. Wonderful person.' 

The president also denied that his strained relationship with Keir Starmer would taint the meeting with Charles, insisting the King was 'not involved in that process'. 

During the trip Queen Camilla will be meeting with domestic and sexual abuse survivors on several occasions. 

And there will be opportunities for the royal couple to meet the American people as part of a series of carefully-managed public engagements.

A Buckingham Palace spokesman said the visit, which is taking place at the request of the British government and has faced repeated calls to be scrapped, came at a perilous time for the so-called 'special relationship'.

They said of the visit: 'This is celebrating a partnership between two nations and two peoples. It is a relationship that has survived many presidencies and, of course, many reigns, and will no doubt continue to do so long into the future.'