Sir Keir Starmer has suffered a major diplomatic blow after Donald Trump publicly sided with Elon Musk amid a furious ongoing row about grooming gangs.

Speaking at a surprise press conference at Mar-a-Lago in Florida, the incoming US president was asked about the tech billionaire’s various comments about European governments and leaders, which have been sparking fury.

When a reporter asked Mr Trump about Mr Musk’s “provocative” posts on X about foreign affairs in Europe, the president-elect replied: “You mean he likes people that tended to be conservative?

“I don’t know the people. I could say Elon’s doing a good job, very smart guy, I don’t know the people you’re talking about.

“I know he said a couple negative things about a couple of people running for office, but that’s not so unusual.”

The comments appeared to be a major snub for Sir Keir, who met Mr Trump prior to his thumping election win in a bid to smooth over potentially difficult relations with the anti-Trump Labour Party.

Sir Keir hit back at Mr Musk during a speech on Monday, in which he accused the world’s richest man of spreading “lies and misinformation” over the child grooming scandal.

The PM also accused the Tesla entrepreneur of amplifying the “poison” of the far-Right.

Since the start of the year, Mr Musk has called Sir Keir “utterly despicable” and said the Labour leader was “deeply complicit in the mass rapes in exchange for votes”.

Mr Musk is set to be a key political player in the coming years after Mr Trump appointed him to head up a new Department of Government Efficiency.

Former UK ambassador to the United States Lord Darroch said Lord Mandelson, the new ambassador, needs to prioritise meeting the X owner to “explain to him calmly and in a friendly manner why he’s wrong”.

Lord Darroch added: “It won’t be easy, but I’ll leave it to the ambassador to try and build a personal relationship with Musk.”

Mr Musk has also singled out Home Office minister Jess Phillips for particular criticism, accusing her of being a “rape genocide apologist” after she rejected a request by Oldham council for a government-led public inquiry into local child sexual exploitation.

Hitting back, Ms Phillips accused Elon Musk’s tweet of increasing threats against her.

She told Newsnight: “Being in the spotlight like this, and the disinformation of what Elon Musk has put out about me, is endangering.”

Ms Phillips said the increase in threats against her makes her feel “resigned to the lot in life you get as a woman who fights violence against women and girls”.