Downing Street has condemned Donald Trump for sharing inflammatory anti-Muslim videos posted online by the deputy leader of the far-right group Britain First.
The US president caused outrage after retweeting to his 43.6 million followers three posts by Jayda Fransen, including unverified footage purporting to show Muslims committing crimes.
The Prime Minister's official spokesman said Britain First was dedicated to causing division among communities and that the president had been "wrong" share the posts.
White House spokeswoman Sarah Huckabee Sanders said Mr Trump had been seeking to "promote strong borders and strong national security".
Pressed on whether the president had a responsibility to verify the content of the postings, Ms Sanders said: "Whether it's a real video, the threat is real and that is what the president is talking about."
The posts included unverified videos titled "Muslim migrant beats up Dutch boy on crutches!" and "Muslim Destroys a Statue of Virgin Mary!"
Fransen, 31, who was convicted last November of religiously aggravated harassment for hurling abuse at a Muslim woman in a hijab, appeared to celebrate the president's actions, tweeting moments later "God bless you Trump".
Elsewhere they caused outrage, with Downing Street making clear the Government's dismay at way he had publicised the views of a such far-right group.
"Britain First seeks to divide communities through their use of hateful narratives which peddle lies and stoke tensions," the Prime Minister's official spokesman said.
"They cause anxiety to law-abiding people.
"British people overwhelmingly reject the prejudiced rhetoric of the far-right which is the antithesis of the values that this country represents, decency, tolerance and respect.
"It is wrong for the president to have done this."
The widower of MP Jo Cox, who was murdered by right-wing extremist Thomas Mair as he shouted "Britain first", said postings were "horrific".
Brendan Cox told the BBC: "Almost nothing Trump does surprises us any more. I think this did.
"I think the revulsion that is out there is because the president of our nearest ally is sharing far right hatred, giving them a microphone, and I think people are authentically shocked by that."
Labour leader Jeremy Corbyn said the postings were "abhorrent, dangerous and a threat to our society", while the Archbishop of Canterbury, the Most Reverend Justin Welby, urged the president to remove them from his timeline.
"It is deeply disturbing that the president of the United States has chosen to amplify the voice of far-right extremists," the Archbishop said.
Despite the outcry, the Prime Minister's spokesman made clear the invitation for the president to make a state visit to the UK, made when Theresa May met Mr Trump in Washington in January, still stood.
"The invitation for a state visit has been extended and accepted.
"Further details will be announced in due course," the spokesman said.
The posts shared by the president appeared to fit a pattern of Britain First re-posting old videos with misleading captions and no information about the date or context.
The first video, which Fransen claimed showed a Muslim migrant attacking a Dutch man on crutches, was also shared by one of Mr Trump's most vocal supporters, conservative commentator Ann Coulter.
The other two videos, which are thought to be from 2013, do not appear in sequence in Fransen's timeline.
It is not the first time Mr Trump has re-tweeted posts from controversial Twitter accounts or shared messages from accounts with apparent ties to white nationalist groups.
One example was his sharing of a tweet about "pizzagate", an unfounded conspiracy theory that claims Democrats harboured child sex slaves at a pizza restaurant.
Fransen, from Penge, south-east London, was fined £2,000 at Luton and South Bedfordshire Magistrates' Court in November 2016 for wearing a political uniform and shouting at Sumayyah Sharpe during a "Christian patrol" of Bury Park in Luton on January 23.
She is currently on bail facing trial over four charges of causing religiously aggravated harassment as part of a Kent Police investigation into the distribution of leaflets and the posting of online videos during a trial held at Canterbury Crown Court in May.
She will also appear in court in Northern Ireland in December charged with using threatening and abusive language in connection with a speech she made at an anti-terrorism demonstration in Belfast on August 6.
Foreign Secretary Boris Johnson tweeted: "Britain First is a divisive, hateful group whose views are not in line with our values. UK has a proud history as an open, tolerant society and hate speech has no place here."