Prime Minister Theresa May on Thursday repeated her condemnation of US President Donald Trump's retweets of anti-Muslim videos posted by a British far-right leader but said US-UK relations would survive the row.

"I'm very clear that retweeting from Britain First was the wrong thing to do," she told a press conference broadcast on British television during a visit to Jordan, before adding that ties with Washington were "enduring".

"We're not afraid to say where we think the US got it wrong," she said, when asked about Trump's reaction to her rebuke on Thursday, in which he said May should focus more on eradicating "destructive Radical Islamic Terrorism" in Britain.

The prime minister also indicated that a state visit by Trump to Britain would proceed, despite calls from many lawmakers that it should now be cancelled.

"An invitation has been extended and has been accepted. We are yet to set a date," she said.

"This is a long-term special relationship that we have... It's in both our national interests," May added.

She focused her criticism on Britain First, saying that the fringe anti-Muslim group "seeks to spread division and mistrust among our communities."

"I think that we must all take seriously the threat that far-right groups pose... In the UK, we take the far-right very seriously," she said.