One royal expert believes US president Donald Trump “won’t give up” when it comes to Prince Harry’s visa row.

A judge ruled last year that Prince Harry’s visa paperwork would not be made public. But a think tank wants the case to be reopened.

In his memoir Spare, the Duke of Sussex referred to taking cocaine, marijuana and psychedelic mushrooms – an admission that prompted conservative think tank The Heritage Foundation to ask if he may have been unfairly granted entry into the US in 2020.

The Duke of Sussex moved to the US in 2020 with Meghan Markle – who is originally from California – and their now-five-year-old son, Prince Archie. The couple have since welcomed their daughter, three-year-old Princess Lilibet.

Speaking on a recent episode of The Sun’s Royal Exclusive, News.com.au’s royal reporter Bronte Coy said his visa fight is “concerning”.

Ms Coy said: “The new US President has made no secret about his position on it. He’s been asked about it so many times over the years.

“I genuinely believe Donald Trump has much more important things to be dealing with. But it’s probably something that’s not going away especially as it continues to get this attention.”

She added: “I think that in itself will be concerning because The Heritage Foundation, who is the one pushing to have the application made public, has also lobbied and urged Donald Trump to intervene.

“It has said this is about accountability and no one is above the law which is also concerning if they maintain that level of profile on the case.”

Speaking prior to his re-election, President Trump said that Harry would be “on his own” if he were voted back into office.

Before he was elected, Mr Trump told the Express US that he would not “protect” Harry, raising questions over what this could mean for his future in the US.

He said: “I wouldn’t protect him. He betrayed the [late] Queen. That’s unforgivable. He would be on his own if it was down to me.”