London - US President Donald Trump warned that a soft Brexit will mean Britain will not be able to make a trade deal with the United States, in a wide-ranging interview with the The Sun, in which he also said Europe was losing its culture because of immigration.
He also waded deeper into domestic politics, supporting Brexit hard-liner Boris Johnson, who stepped down as foreign secretary this week, saying "he has got the right attitude to be a great prime minister." Trump said he was "very surprised and saddened" when Johnson resigned.
"Well, if they do a deal like that they most likely, because we will be dealing with the European Union instead of the UK. So it will probably kill the deal… If they do that their trade deal with the US will probably not be made," the US president said, without being more specific.
"If they do that would probably end a major trade relationship with the United States," Trump said, adding that the US was now "cracking down" on the EU over trade, referring to new tariffs he imposed.
The Rupert Murdoch-owned tabloid released audio recordings from the interview. The paper wrote that Trump was referring to attempts to maintain close ties to Europe.
Chances of US trade deal
Trump said he "told Theresa May how she should" handle the negotiations, but the prime minister did not listen to him.
"I think the deal she is striking is not the deal people voted on, it is not the deal that was in the referendum," Trump said.
Trump used the interview to hit out at the mayor of London, Sadiq Khan, a major critic of the US president, saying: "I think he’s done a bad job on terrorism, I think he did a bad job on crime." He tied this his general attacks on immigration to Europe.
"I think what has happened to Europe is a shame. Allowing the immigration to take place in Europe is a shame," Trump said. "I think it changed the fabric of Europe."
Trump went on: "Allowing millions and millions of people to come into Europe is very very sad. I think you are losing your culture."
Trump appeared upset over protests in the British capital, saying there was "no reason for me to go to London... When they make you feel unwelcome why would you stay there."
Evoking Churchill's words
Earlier, the British prime minister invoked British World War II leader Winston Churchill as May welcomed Trump to the country with a call for a post-Brexit free-trade deal between the two nations.
"To have the United States at our side was, to me, the greatest joy," May quoted Churchill as saying.
"Now, for the benefit of all our people, let us work together to build a more prosperous future," she told Trump.
Trump had left London on Thursday night on a short helicopter flight to Blenheim Palace, Churchill's birthplace near Oxford, where May hosted a welcome dinner and a military parade in his honour.
Wearing a tuxedo, Trump boarded the aircraft at Winfield House, the US ambassador's residence in London's Regent's Park, where he was scheduled to return to stay on Thursday night.
He was accompanied by his wife, Melania, who wore a yellow evening dress, and by Ambassador Woody Johnson and his wife.
Hundreds of protesters had gathered outside Blenheim Palace ahead of Trump's arrival, after smaller protests in London earlier and larger ones planned for Friday, when organizers hope to attract tens of thousands to central London.
Two protesters outside Blenheim Palace held up a large sign reading: "Get your tiny, groping, racist hands off our NHS (National Health Service) Mr President."
Their message reflects fears that, as part of any trade deal, Trump could demand far greater access to Britain's healthcare industry for US Medicare, pharmaceutical and other firms.
May said British companies had already created hundreds of thousands of "jobs, opportunities and wealth for hard-working people right across America."
"Now, as we prepare to leave the European Union, we have an unprecedented opportunity to do more," she said, according to advance excerpts of her speech.
"It's also an opportunity to tear down the bureaucratic barriers that frustrate business leaders on both sides of the Atlantic."
May said earlier Thursday that she plans to use Trump's four-day visit to "begin discussions about how we will forge a strengthened, ambitious and future-proof trade partnership."
Johnson has said that a free-trade deal with Britain was "a major priority" for Trump.
He said the two leaders would also discuss military and intelligence cooperation amid growing security threats from nations including China, Russia, North Korea and Iran.
Trump's visit was apparently postponed last year amid strong opposition in Britain.
He stirred controversy earlier Thursday before leaving for London from Brussels, where he attended a NATO summit, by questioning whether under-pressure May is giving voters "what they voted for" in the 2016 Brexit referendum.
Trump had already raised eyebrows on Tuesday after saying he would be visiting a Britain "in turmoil."
He is due to conduct his main talks with May on Friday at Chequers, the British prime minister's retreat outside London, followed by a joint press conference.
Trump will also meet Queen Elizabeth II later Friday at Windsor Castle, a royal palace outside London, before visiting Scotland on Saturday.