The home secretary has warned that anyone engaging in “unacceptable disorder” will pay the price, following unrest in several cities across England.
Yvette Cooper said she would work with police forces to help ensure “consequences, arrests and prosecutions” for those responsible.
A wave of demonstrations took place on Saturday, some of which saw bottles thrown, windows smashed and scuffles with officers and counter-protesters – but not all demonstrations turned violent.
Tensions have been high after the killing of three young girls at a Taylor Swift-themed dance party in Southport, Merseyside, on Monday.
Several police forces reported that officers had been injured while policing demonstrations.
Speaking on Saturday, Yvette Cooper said “criminal violence and disorder has no place on Britain’s streets”.
Police have the government’s full backing in taking action against those engaging in “thuggery”, she added.
Some suspects have already been arrested and are in custody, with more arrests expected, she said.
People engaging in violence face “imprisonment and travel bans” amongst other punishments, she said, adding that “sufficient” prison places have been made available.
People have “the right to feel safe”, Ms Cooper added.
In Liverpool, bricks, bottles and a flare were thrown at police, one officer was hit in the head when a chair was thrown, and another was kicked and knocked off his motorbike.
The protest was centred around the city’s waterfront, with the atmosphere feeling chaotic at times as police struggled to remain in control.
Less than a mile away, a few hundred anti-fascist demonstrators gathered across from Liverpool’s Lime Street station at lunchtime, calling for unity and tolerance, chanting “refugees are welcome here” and “Nazi scum, off our streets”.
They marched down to the Pier Head to confront around a thousand anti-immigrant protestors. Police in riot gear with dogs struggled to keep the two sides apart.
Smoke canisters, bottles and paint tins were thrown by people chanting anti-immigrant slogans, some of them masked.
A number of arrests were made and police reinforcements arrived in vans to try to maintain order. A police plane was seen circling overhead.
Shoppers and visitors to Liverpool’s iconic waterfront appeared surprised to see the crowds. Many were wondering what any of this has to do with the awful events in Southport on Monday.
Merseyside Police confirmed a number of officers have been injured in what they described as “serious disorder” in the city centre.
“There is no place for this despicable behaviour,” the force added.
In Hull, protesters smashed a window at a hotel that has been used to house asylum seekers, and bottles and eggs were thrown at police. Humberside Police said three police officers had been injured and four people arrested amid disorder in the city centre.
In Manchester, there were scuffles with police, and at least one arrest. While in Belfast, protesters outside a mosque threw objects at members of the media and earlier smashed windows in a cafe.
In Blackpool, protesters faced off against punks attending Rebellion Festival. The Press Association news agency reported there was little police presence as skirmishes broke out between the two groups, with bottles and chairs thrown.
Not all demonstrations held across the UK descended into violence on Saturday, and in some places protesters have dispersed already. Others are scheduled for later in the day.
A spokesperson for Prime Minister Sir Keir Starmer said the police have his “full support” to take action against “extremists” attempting to “sow hate”.
Saturday’s protests follow a night of violence in Sunderland on Friday, which saw four police officers hospitalised and 10 people arrested.
Hundreds of people rioted, beer cans and bricks were thrown at riot police outside a mosque and a Citizens Advice office was torched.
Twelve people have been arrested in connection with the violence.
In Sunderland, some members of the crowd could be heard shouting Islamophobic slurs and chanting in support of far-right activist Tommy Robinson, founder of the now disbanded English Defence League (EDL).
The X account of Robinson, an alias for Stephen Yaxley-Lennon, has promoted false claims that the alleged Southport attacker had been an asylum seeker who recently arrived in the UK by boat.
Towns and cities including London, Hartlepool, Manchester, and Aldershot have seen protests descend into violence in recent days, following the Southport knife attack, which also left seven other children and two adults injured.
South Wales Police issued a dispersal order in Cardiff on Saturday, in an area around Mermaid Quay and the Senedd.
The BBC has identified at least 30 demonstrations being planned by far-right activists around the UK over the weekend, including a new protest in Southport.
An extra 70 prosecutors are on standby this weekend to charge people arrested in connection with violent disorder.
Shadow home secretary James Cleverly called on Sir Keir and home secretary to “do more” to restore public order and “send a clear message to the thugs”.
Earlier this week, the prime minister announced a new national violent disorder programme to help clamp down on violent groups by allowing police forces to share intelligence.
With additional reporting by BBC News reporters across England.