UK Home Secretary Sajid Javid urged public figures to "moderate their language".

Britain's interior minister Sajid Javid on Friday recalled being told "to go back to where I came from" as a child, condemning extremist language after comments by US President Donald Trump.

Trump faced accusations of racism this week when he tweeted that four Democrat congresswomen -- all US nationals -- could "go back" to the countries from which they came.

Prime Minister Theresa May earlier condemned Trump's language as "completely unacceptable".

Javid, whose Muslim parents moved from Pakistan to Britain before he was born in 1969, urged public figures to "moderate their language".

Launching a review into Britain's counter-extremism strategy, he said anti-immigrant rhetoric was stoking dangerous division.

"Around the world, populism and even open racism have catapulted extremists to power," he said.

"I'm from an immigrant family. I know what it's like to be told to go back to where I came from," said Javid, recounting feeling scared, angry and confused.

"We must confront the myths about immigration that extremists use to drive divisions," he said.

"We know the scale is exaggerated to stoke up fear and that they use immigration as a proxy for race."

According to the latest Office for National Statistics (ONS) figures, immigration ran at 627,000 in the year to September 2018, with net migration at 283,000.

Net migration from European Union countries has fallen to a level last seen in 2009, while non-EU net migration is at the highest level since 2004.

Immigration was a key factor in Britain's vote to leave the EU. The ONS UK population estimate for mid 2018 was 66,436,000.

Javid said the extremism problem has spread from radicalisation by groups like Islamic State to the far left and right of politics.

"Public discourse is hardening and becoming less constructive," he said.

"Everyone has a part to play: broadcasters who must not give a platform to extremists; police who must swoop on the worst offenders; public figures who must moderate their language."