Violent disorder in towns and cities led to officers being injured as bricks, chairs and bottles were thrown at police.
Prime minister Keir Starmer said the police had his “full support” to take action against “extremists” attempting to “sow hate” by intimidating communities as he held emergency talks with ministers over the unrest in parts of England.
Home secretary Yvette Cooper said those engaging in violence “will pay the price” and “criminal violence and disorder has no place on Britain’s streets”.
Cities in England and Northern Ireland saw clashes between anti-immigration demonstrators and counter-protesters on Saturday, with police forming lines with riot shields to keep groups apart.
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The far right has drawn condemnation from MPs across the political spectrum after disorder in London, Manchester, Southport and Hartlepool over the past three days.
Merseyside Police said a number of officers were injured during “serious disorder” in Liverpool city centre, with one officer being hit on the head by a chair.
Bricks, bottles and a flare were also thrown at officers as they lined The Strand in the city centre.
Another officer was kicked and knocked off his motorcycle by a demonstrator and others tried to kick riot shields.
In Hull, four people have been arrested as three officers were hurt after a group of people targeted a hotel which houses asylum seekers.
Humberside Police chief superintendent Darren Wildbore said officers had “faced eggs and bottles being thrown” as windows were smashed at the hotel which has housed migrants.
Elsewhere, bricks were thrown at officers in Stoke-on-Trent and fireworks were thrown amid tense exchanges between an anti-Islamic group and an antiracism rally in Belfast.
Four men have been arrested following disorder in the Staffordshire city.
And scuffles broke out as opposing groups faced each other in Nottingham’s Market Square with bottles and other items thrown from both sides, and chants of “England till I die” and “Tommy Robinson” were drowned out by boos from counter-protesters.
At least three people were led away in handcuffs in the East Midlands city.
About 150 people carrying St George flags shouting “You’re not English any more” and “Paedo Muslims off our street” were greatly outnumbered in Leeds by hundreds of counter-protesters shouting “Nazi scum off our streets”.
Skirmishes broke out between demonstrators and punks in Blackpool, with bottles and chairs being thrown and wood wielded.
The string of violent incidents began in Southport on Tuesday, where demonstrators attacked police and set cars on fire the day after three girls were killed in a knife attack at a Taylor Swift-themed holiday club.
Axel Muganwa Rudakubana, 17, from Lancashire, is accused of the attack, but false claims spread online that the suspect was an asylum seeker who had arrived in the UK by boat.
Thousands of people had turned out to pay their respects to Bebe King (6), Elsie Dot Stancombe (7) and Alice Dasilva Aguiar (9) at a vigil in Southport on Tuesday. Violence later erupted outside a mosque in the town and 53 police officers and three police dogs were injured. - PA