Authorities have called for calm after a “savage and barbaric” knife attack in Belfast, Northern Ireland, that has sparked unrest on the streets, with houses targeted and vehicles blown up.

A man, who police said was Sudanese, was charged with attempted murder after he was seen thrusting a knife at the neck of a 40-year-old victim on Monday night.

The horrific incident was captured on video, showing the victim on the ground as bystanders yell “he’s trying to cut his head off” and “get off him”.

In footage being shared online, the alleged attacker straddles the bloodied victim and at one point raises his arm into the air and cries out.

The video shows bystanders attempting to halt the gruesome stabbing before police arrive to intervene.

The alleged attacker is seen straddling the victim. Photo: X

British Prime Minister Keir Starmer said it was a “savage and barbaric attack” and he had “no tolerance for abhorrent scenes of violence like this on our streets”.

Police said the victim had significant eye injuries and serious slash wounds to his back and face.

A knife, believed to be a kitchen knife, was found at the scene, said police.

It comes after national backlash in Britain last week when video was released of student Henry Nowak, 18, who was handcuffed as he lay dying after his killer, a Sikh man, falsely alleged a racist attack.

The killer Vickrum Digwa, 23, was sentenced to life in prison, having lied to police at the time that Nowak had assaulted him.

In police bodycam footage, Nowak is seen lying on the street saying “I’ve been stabbed” and “I can’t breathe” while an officer responds, “I don’t think you have, mate”.

Bystanders filmed the shocking incident before police intervened. Photo: X

Authorities in Belfast have called for calm amid fears that the incident would be whipped up by right-wing, anti-immigration agitators.

The Home Office confirmed that the arrested man was a Sudanese national who was granted refugee status in 2023 and had leave to remain until 2028.

Media outlets report that after the frightening attack, people began gathering in the streets as authorities urged them to stay at home and close their businesses.

In one unionist area of Belfast bins were set alight, with thick black smoke rising into the sky, and two explosions were heard on a bus.

Young men wearing masks or balaclavas were on the streets, and in other parts of the city people were gathering in protest.

A bus set on fire by protesters during an anti-immigration demonstration after the stabbing. Photo: AAP

First Minister Michelle O’Neill urged the people of Belfast not to let outsiders stir up rage.

“Don’t let other people, who don’t care about here, incite hatred and fear,” she said.

“Don’t allow people who are faceless to orchestrate campaigns on the street.”

Police said they were aware of calls for protests and were monitoring the situation.

Assistant Chief Constable Ryan Henderson, of Police Service Northern Ireland, said the brutal attack would send “shockwaves through the community causing real concern”.

“I want to reassure the local community that we are treating this attack with the utmost seriousness,” he said.

“Our investigation is continuing at pace.”

The leaders of Northern Ireland’s five main political parties issued a joint statement calling for calm and urging justice to take its course.

“There is no place in our society for this kind of brutality,” they said.