Downing Street has hit out at "people trying to interfere in our democracy and seeking to stir up division", after JD Vance's comments on the murder of Henry Nowak.
The US vice-president blamed the death of the 18-year-old British student, who was fatally stabbed last year in Southampton by Vickrum Digwa, on the "mass invasion of migrants" and said the "only response" was "righteous anger".
After the post on X, the Downing Street spokesman said the Nowak family had "said they do not want his death to be used to create further division".
"Our politics should bring people together even in the most terrible of circumstances. That is who we are as a country," the statement added.
Violent protests took place in Southampton on Tuesday following the release of bodycam footage which showed police handcuffing Nowak as he lay dying after Digwa falsely claimed to be the victim of a racist attack.
Digwa was jailed for life with a minimum of 21 years after he used a 21cm (8in) blade he said he carried as part of his Sikh faith to kill Nowak, who was walking home alone after a night out with friends on 3 December.
In his post, Vance said Nowak had died "the same way a civilisation dies: abandoned and handcuffed by authorities who neither trusted nor cared for him".
The killing had been as "tragic as it is enraging" and Nowak, he said, would still be alive today "if the last few generations of European elites had stood their ground against the politics of self-hatred and the mass invasion of migrants".
The Crown Prosecution Service has confirmed that Digwa was born British.
The Minister for Children and Families, Josh MacAlister, also appeared to criticise Vance when he appeared on BBC Radio 4's Any Questions programme.
"There are people who are trying to import that kind of toxic politics here into the UK and I don't want to have anything to do with it," he said.
"I don't think we need advice from American politicians... [on] how to have effective policing here in the UK," he added.
On Friday, Conservative leader Kemi Badenoch called for an "independent rapid review" into the circumstances surrounding Nowak's death.
In a letter to the Prime Minister, Sir Keir Starmer, on Friday, she wrote: "The questions raised about what followed are of profound public importance.
"They concern not only what happened to Henry but overall public confidence in policing and the ability of our institutions to protect those they exist to serve."
The Independent Office for Police Conduct is already investigating police officers' behaviour, while an inquest jury is to consider next year whether "any act or omission by police officers" or delay in treatment caused or contributed to Nowak's death.
Earlier this week, Sir Keir accused tech billionaire Elon Musk of "trying to whip up division" over Nowak's murder.
Posting on X on Tuesday, Musk had written: "Send the video to everyone you know showing how heinously Nowak was treated by the police in his dying moments and how the police cravenly kowtowed to his murderer."
He had also accused the mainstream media who wrote about George Floyd "millions of times" of being "dead silent about Nowak".
Floyd died of a cardiac arrest in the US in May 2020 after a police officer handcuffed him before kneeling on his neck. His murder sparked global protests against racism and police brutality.
Vance's comments appear to be partly aimed at a US audience. During his second term, Donald Trump has carried out sweeping efforts to deport undocumented migrants - a key election promise that drew both mass support and criticism from detractors during the campaign.
The US president has also frequently tied the influx of migrants to the erosion of national identity.
Reacting to Vance's comments on BBC Radio 4's Today programme, Republicans Overseas spokesperson Jennifer Ewing said they come "from a place of care and concern".
She explained: "All we want is for the people of the UK to be heard by politicians", and pointed out that Vance has previously expressed concerns about the UK's stance on "free speech" and "unfettered immigration".
Current and former Trump administration officials have repeatedly weighed in on British domestic issues.
This included the president's attacks on energy policy and immigration, and a formal warning to the UK about its handling of "rape gangs".
Most figures in UK politics had hoped the atmosphere would remain calmer after the violent protests in Southampton on Tuesday.
A reason the criticism from Downing St was so swift and pointed is in part to avert what could become another political storm.
Since the Iran war began, Downing St has been more content to talk openly about disagreements.
Nonetheless, the UK government has in parallel continued to stress there is continued and deep co-operation on security.
The comments by Vance follow a week in which there has been intense scrutiny of the police response.
Debate over the case escalated during PMQs on Wednesday, when Sir Keir accused Reform UK leader Nigel Farage of exploiting the death of Nowak to create "grievance and division".
Farage, who reposted Vance's remarks without comment, had argued the incident was the result of "two-tier policing", citing anti-racism guidance issued by police bosses.
"Two-tier policing" is the claim that minority communities are treated preferentially because officers are worried about being accused of racism.
The acting chief of West Midlands Police, Constable Scott Green, has rejected its existence.
Sir Ed Davey, leader of the Liberal Democrats, said "we all need to resist attempts like this to politicise Henry Nowak's death and divide our country - whether they come from MAGA politicians like Vance or their cronies here in the UK".
Meanwhile Labour peer Thangam Debbonaire called Vance's comments "unhelpful".
"When you make extremist statements without supporting them with evidence, you are stoking up the division that Henry Nowak's family explicitly said they did not want," she told the Today programme.
Additional reporting by Jamie Whitehead
