London — Hundreds of protesters clashed with law enforcement in southern England on Tuesday — angry over the murder of 18-year-old Henry Nowak and the way he was treated by police.

Right wing activists joined the protest, including Tommy Robinson, a British anti-immigration campaigner with multiple criminal convictions.

Nowak, a university student, was stabbed five times by Vickrum Digwa last December after an argument in the city of Southampton. 

Digwa was convicted of murder last week and sentenced to life in prison.

Police body-cam video shows officers handcuffing Nowak as he lay dying. He can be heard telling them that he had been stabbed, but they didn't believe him, and continued forcing him into handcuffs as he pleaded that he was unable to breathe.

Digwa claimed he was the victim of racist abuse that led to the deadly encounter, though the court determined that he had lied about that.

Nowak's father called his son's treatment by police inhumane and degrading.

"With his final words, he told them that he could not breathe. He told them he had been stabbed," said the bereaved father. "In fact, Henry told the officer that he could not breathe nine times."

British Prime Minister Keir Starmer said there were serious questions for the police to answer.

"I have seen the body cam footage. It's harrowing," he said. "And I have to say, as the father of a 17 year-old boy, I felt sick."

The emotion boiled over on Tuesday during the protests. One group of protesters clashed with riot police, hurling rocks and flares, near the scene of the killing, shouting: "I can't breathe."

Britain's rising right-wing, anti-immigration political movement has seized on the case to spread its message. 

One of that movement's leaders, Nigel Farage of the Reform UK party, pointed to it as evidence of "two-tier policing," a popular far-right claim that ethnic minorities get better treatment than white people.

Farage called for "pure cold rage" over the incident, and demanded an end to what he claimed is "anti-white prejudice" in Britain.

U.K. Home Secretary Shabana Mahmood, who's responsible for law enforcement in the country, rejected the notion that police have different standards for different communities and she urged lawmakers not to "allow this murder to turn communities against one another."

Mahmood said she understood that people were horrified by the video of Nowak's killing, and stressed the government's efforts to reduce knife crime.

She called for calm as an investigation by the Independent Office for Police Conduct looks into the actions of the officers involved, and she warned that "misinformation and inflammatory commentary" online was making "a dreadful situation even worse."

Police officers who weren't even involved in the deadly incident were getting death threats, Mahmood said.

Nowak's father has said he does not want his son's death "to be used to create further division, hatred or tension."