WASHINGTON (AFP, REUTERS) - Mr Donald Trump has tweeted that Brexit campaigner Nigel Farage "would do a great job" as British ambassador to the US, in the latest unorthodox intervention from the President-elect.

The decision on who is appointed to represent the United Kingdom in Washington is a matter for the British government, but that did not stop the controversial property mogul-turned-world leader from weighing in on social media.

"Many people would like to see @Nigel-Farage represent Great Britain as their Ambassador to the United States," Mr Trump said on his Twitter account. "He would do a great job!"

But British Prime Minister Theresa May's office pointedly ruled out such a move. "There is no vacancy," a Downing Street spokesman said when asked about Mr Trump's remark on Tuesday (Nov 22). "We already have an excellent ambassador to the US."

Mr Farage said on Tuesday he was in a good position to help Britain build ties with Mr Trump. "I have known several of the Trump team for years and I am in a good position with the President-elect's support to help," Mr Farage, leader of the opposition UK Independence Party (UKIP), wrote in a column for the Breitbart website. "The world has changed and it's time that Downing Street did too," he said, referring to Prime Minister May's office.

Mr Farage recently met the President-elect at Trump Tower in New York.

"It was a great honour to spend time with @realDonaldTrump," Mr Farage tweeted at the time, posting a photo of the pair standing before a gilded doorway. "He was relaxed and full of good ideas. I'm confident he will be a good President."

During the divisive US presidential campaign, Mr Trump repeatedly compared his presidential bid to the Brexit referendum in which a majority of Britons voted to split from the EU.

Mr Trump's call on Twitter is unusual - ambassadors are appointed by the governments they represent, not by the administration of the country in which they serve.

Britain is keen to build bridges with Mr Trump after many leading government figures criticised the President-elect during his successful election campaign.

London is also interested in sounding out a US trade deal as it plots its departure from the European Union.

Queen Elizabeth II could host Mr Trump within months of him becoming United States president, with the British government confirming on Monday (Nov 21) that it was considering a state visit next year.

Royal officials said that the government was responsible for organising state visits, and a spokesman for Mrs May said that the proposal was "under consideration".

Mr Trump told Mrs May that he was a "big fan of the Queen" when the pair spoke by telephone following his victory, and is also reported to have told Mr Farage that his late mother Mary would be "chuffed to bits when I meet the Queen".

Britain will not issue an invitation to a president-elect, but is expected to make its move shortly after Mr Trump's inauguration on Jan 20.