US President-elect Donald Trump has confirmed he will hold his first meeting with British Prime Minister Theresa May this year, saying he was "very much" looking forward to it.

"I look very much forward to meeting Prime Minister Theresa May in Washington in the Spring. Britain, a longtime US ally, is very special," Trump tweeted on Saturday.

The introduction was organised after meetings with May's closest advisers over Christmas, the BBC reported.

A date for the meeting has not yet been confirmed, but is expected to come within weeks of Trump's inauguration on January 20.

May and Trump spoke twice since his November 8 election victory, and May's joint chiefs of staff Nick Timothy and Fiona Hill travelled to the US in December to meet Trump's team.

Earlier, May praised Trump as "very easy to talk to", despite having criticised him during the US elections.