Prince Harry and Meghan Markle are asked to stay strictly mum over US politics.

The Duke and Duchess of Sussex, who have refrained from taking sides as Kamala Harris and Donald Trump continue their presidential bid, are warned against any volatile step.

Royal expert Hugo Vickers told The Sun: "It's a big danger issue for them.

"I think that everything they do is a desperate attempt to keep relevant and keep themselves in the news,” he said.

"You could say it's very trivial to put out a notice saying: 'Go out and vote,' we know people should do that. It's not really up to them to tell the American population how they should spend their time, or what they should do at all.

Mr Vickers noted: "But in that respect I do see them sort of once again, weighing in and seeking publicity, because that's how they stay relevant.

They've moved into this kind of celebrity status situation, whereby they must always be attracting news comments, otherwise they disappear.

"But they definitely should not be dabbling in any kind of politics, least of all American politics. They have really no right to do it,” he added.