Donald Trump will not visit the UK this year, the White House has confirmed.

Press Secretary Sarah Huckabee Sanders said it "still hasn't been determined" whether the US president would make a full state visit to Britain, following reports a planned trip had been downgraded.

Prime Minister Theresa May made the offer of a state visit - an honour usually reserved for a president's second term - seven days after his inauguration in January, when she became the first foreign leader to visit him in the White House.

It prompted a wave of criticism and threats of mass protests.

Mr Trump has subsequently visited France and Germany, but the president has yet to fly to London and diplomats were said to be discussing plans for a less controversial working trip, which would mean Mr Trump did not meet the Queen.

Ms Sanders told a press briefing that Mr Trump was would visit Britain "sometime next year".

Asked if the trip would be "a working visit or a state visit", the White House press secretary said: "That still hasn't been determined. We're still going back and forth with our allies there. And once we have those travel details outlined and determined, we'll certainly let you know.

"But they've made the invitation for the President to come. We've accepted and we're working out the logistics."

She added: "We anticipate that it will be sometime next year. But at this point, there's no other details beyond that."

Theresa May talks with Donald Trump during the G20 leaders' summit in Hamburg (REUTERS) (Reuters)

Mr Trump was reported to have told Ms May earlier this year that he would not make a state visit to the UK until he is guaranteed a warm welcome.

More than 1.8 million people signed a petition against his invitation and House of Commons Speaker John Bercow told MPs that Mr Trump should not be allowed to address Parliament.

London mayor Sadiq Khan also opposed the visit, saying he was “not sure it is appropriate for our government to roll out the red carpet” for such a controversial figure.