Michael Wolff, the author of an explosive new book about Donald Trump's administration, has suggested the US president might withhold a crucial trade deal with the UK if he is not invited to Prince Harry's wedding to Meghan Markle.

Prince Harry is reportedly reluctant to invite Trump to his wedding and is friendlier with the president's predecessor, Barack Obama, joking around with him in public and interviewing him for the BBC.

Wolff told the Mail on Sunday newspaper that Trump sees his upcoming state visit the UK as an opportunity to outshine the Queen, who he regards as a reality TV-style rival.

Some critics have said Wolff's book, "Fire & Fury: Inside the White House", is not entirely accurate and even Wolff has said he's not sure if everything he's written is true.



US president Donald Trump really wants to go to Prince Harry's wedding to actress Meghan Markle.

So much so, he's apparently threatening to withhold a vital post-Brexit trade deal with the UK if he doesn't receive an invitation to the royal nuptials.

That's according to Michael Wolff, author of the explosive new "Fire & Fury: Inside the White House" book, which digs into the Trump administration.

Wolff made the suggestion to the Mail on Sunday in an interview saying that Trump "doesn't like being snubbed and wants to be the centre of attention all the time."

He said Trump would only "value the Brits" if the UK gives him what he wants.

Trump has a standing state invitation to the UK, and is expected to visit the country at some point.

But Wolff said Trump was primarily interested in turning the visit into a reality TV spectacle — and that he saw the Queen as a major rival.

"He sees the Queen in reality TV show terms. That’s the Trump modus operandi. He will try to Trumpalise the Queen and Buckingham Palace."

It isn't clear that Prince Harry will oblige, even for a crucial trade deal. He is publicly on much friendlier terms with Trump's predecessor, Barack Obama, joking around with him at the Invictus Games in September and even interviewing him for the BBC.

Prince Harry with former US president Barack Obama. Win McNamee / Getty

Wolff also claimed that Trump has scant regard for the UK's historical "special relationship" with the US, and didn't understand what Brexit was in the weeks before the referendum last year.

He also repeated claims that Trump is mentally unstable, and might even have dementia.

One of the main claims in "Fire & Fury" is that 100% of Trump's staff question his intelligence, mental capacity, and fitness for office. Early on Saturday, Trump went into meltdown on Twitter as the claims became public.

"Actually, throughout my life, my two greatest assets have been mental stability and being, like, really smart," he wrote in one post. "Crooked Hillary Clinton also played these cards very hard and, as everyone knows, went down in flames. I went from VERY successful businessman, to top T.V. Star ... to President of the United States (on my first try). I think that would qualify as not smart, but genius....and a very stable genius at that!"

In an interview with the BBC on Sunday morning, UK prime minister Theresa May wouldn't comment on the speculation on Trump's mental health. She confirmed he would be visiting the UK.

"Obviously I've worked with President Trump on a number of issues [...]. What I make of him is somebody who is taking decision on what he believes are in the best interest of the US."

She added: "He will be coming to this country."

Wolff claims his book is based on more than 200 interviews with people close to the Trump administration, though many have publicly disputed the quotes he attributes to them. Even Wolff has admitted he can't be sure everything in the book is entirely true.