Riots involving hundreds of anti-immigration protesters have erupted in several towns and cities in recent days after false information spread rapidly on social media that a suspect in Monday's knife attack at a dance class for children in Southport was a radical Muslim migrant.
Police have said the suspect, Axel Rudakubana, 17, was born in Cardiff, Wales but protests by anti-immigration and anti-Muslim demonstrators have continued, descending into violence and rioting, most recently in the northeastern city of Sunderland on Friday evening.
Police in Liverpool said on Saturday that a number of officers had been injured while dealing with "serious disorder" in the city centre.
Authorities in the eastern city of Hull said four people were arrested and three officers were injured while dealing with protests where bottles were thrown.
Mosques across the country have been advised to strengthen security while police have deployed extra officers.
Rival groups have clashed in some cities across the United Kingdom amid a tense atmosphere. (AP PHOTO)
Prime Minister Keir Starmer, facing his first big test since being elected a month ago, has condemned the "far-right" for the violence and backed police to take strong action.
He discussed the disorder with senior ministers on Saturday, his office said.
The last time major widespread violence erupted in the UK was in 2011 when thousands took to the streets for five nights after police shot dead a black man in London.
Reuters witnesses in Liverpool, Leeds, Manchester and Belfast reported a tense atmosphere on Saturday as police tried to keep several hundred rival protesters who were chanting slogans from clashing.
Scuffles and violence broke out in some cities including in Nottingham and Liverpool, where eggs, beer cans and smoke grenades were thrown while in Belfast some businesses reported damage to property.
"I have no reason why they attacked us," said Rahmi Akyol, standing outside his cafe in Belfast, whose glass doors were shattered after being attacked by dozens of people throwing bottles and chairs.
"I've lived here 35 years. My kids, my wife is from here. I don't know what to say, it's terrible," he said.
At protests in London, police arrested several people including one for making a Nazi salute towards a counter-protester.
On Friday night hundreds of anti-immigration demonstrators in Sunderland threw stones at police in riot gear near a mosque before overturning vehicles, setting a car alight and starting a fire near a police station.
Four injured police officers were taken to hospital and 12 people were arrested, Mark Hall, chief police superintendent of the Sunderland area, told reporters on Saturday.
"This was not a protest. This was unforgivable violence and disorder," Hall said.
At least 30 demonstrations were being planned across the UK this weekend, the BBC said, along with a number of counter-protests by anti-racism groups.
