DONALD Trump said he has apologised to Theresa May for humiliating her in a newspaper interview.

In an embarrassing and astonishing interview with The Sun, the US President said he thought Boris Johnson would make a good Prime Minister, and that May’s new Brexit plan would "kill" any UK-US trade deal. He also claimed to have given May advice on how to negotiate with the EU, but that she'd ignored it.

Trump, who is on day two of a four-day trip to the UK, infuriated supporters of his host.

And then at an extraordinary press conference on Friday afternoon at Chequers, Trump at first appeared to say the interview, which was taped, was “fake news”. But he then admitted he’d said everything he’d been quoted as saying and that he hadn’t read past the headlines before making his comments.

He then told the press gathered at the Prime Minister's country estate that he’d apologised to May, but that she’d replied: "Don't worry it's only the press."

In his interview with The Sun, which was conducted earlier this week but only published this morning, Trump said he would have carried out the UK's Brexit negotiations "much differently" and claimed the Prime Minister did not listen to his advice.

Referring to the approach to talks with the EU agreed by May's Cabinet a week ago, he said: "If they do a deal like that, we would be dealing with the European Union instead of dealing with the UK, so it will probably kill the deal. If they do that, then their trade deal with the US will probably not be made."

Trump went on to say that Johnson, who quit as foreign secretary over the Prime Minister's post-EU trade plan, was "a great representative for your country".

Asked if he thought Johnson could become prime minister, Trump added: "Well I am not pitting one against the other. I am just saying I think he would be a great prime minister. I think he's got what it takes."

Asked about the interview at the press conference, Trump said The Sun story was "generally fine" but missed out his positive comments about May.

He also promised to release a recording of the interview so people could hear all the “nice things” he said about May.

Trump said he believed it was possible to do a trade deal with the UK after Brexit.

He said: "The only thing I ask of Theresa is that we make sure we can trade and we don't have any restrictions because we want to trade with the UK and the UK wants to trade with us.

"We are by far their biggest trading partner and we have just a tremendous opportunity to double, triple, quadruple that.

"So if they go in a slightly different route - and I know they do want independence, it's going to be independence, it's just your definition - if they are going to go in a certain route I just said that I hope you are going to be able to trade with the United States.

"I read reports where that won't be possible, but I believe, after speaking with the Prime Minister's people and representatives and trade experts, it will absolutely be possible."

Asked if he thought Johnson would be a "great prime minister," Trump replied: "He's been very nice to me. He's been saying very good things about me as president.

"I think he thinks I'm doing a great job. I am doing a great job, I can tell you, just in case you haven't noticed.

"Boris Johnson, I think, would be a great prime minister."

Trump added: "I also said that this incredible woman right here is doing a fantastic job, a great job. I mean that. And I must say, I have gotten to know Theresa May much better over the last two days than I have known her over the last year-and-a-half."

"I think she's a terrific woman. I think she's doing a terrific job. And, that Brexit is a very tough situation, that's a tough deal."

He added: "She's going to do the best. The only thing I ask is that she work it out so that we can have very even trade because we do not have a fair deal with the European Union right now on trade."

The president said he hadn’t given May advice, but rather a suggestion. He didn’t say what that suggestion was, but said May “found it maybe too brutal”.

He added: "I can fully understand why she thought it was a little bit tough and maybe someday she will do that - if they don't make the right deal she might very well do what I suggested that she might want to do."

May said: "Lots of people give me advice about dealing with the European Union. My job is actually getting out there and doing it."

At one point Trump refused to take a question from the CNN.

He told its reporter: "CNN is fake news, I don't take questions from fake news. Let's take a question from a real network."

The president also repeated the claim that he had been in Scotland the day before the EU referendum and had predicted the Brexit vote. That is incorrect. He was in Scotland the day after the EU referendum.

Trump and First Lady Melania now head to Windsor Castle to meet the Queen, before he comes north to Scotland.