Jul 13, 2018 11:42 Asia/Tehran

Donald Trump’s first official visit to the UK got off to a shaky start on Thursday after the president said Theresa May’s Brexit plan would “kill” a free trade deal with the US.

The U.S. President also praised Boris Johnson and said Theresa May ignored his advice on Brexit negotiations in an extraordinary interview with The Sun newspaper.

The interview even threatened to undermine Theresa May's  new Brexit  strategy, painfully thrashed out with her cabinet last week.  Trump even questioned whether her plans upheld the referendum result and accused her of ignoring his advice.

Against a backdrop of protests and demonstrations nationwide against his visit, the US president openly humiliated May by suggesting that former foreign secretary Boris Johnson, who quit in opposition to her Brexit plans this week,  would make a great prime minister.

On Thursday evening, as Theresa May told a dinner held in Donald Trump’s honour at Blenheim Palace that her policy would create an “unprecedented opportunity” for a free trade agreement, his damaging statements were revealed.

Asked about Trump’s incendiary interview with The Sun newspaper, White House press secretary Sarah Sanders insisted the president “likes and respects Prime Minister May very much”.

In the interview, which ignores all usual diplomatic conventions, Donald Trump warned that May's  soft Brexit approach would scupper any hopes of a free trade agreement with the United States.