British Prime Minister Boris Johnson has said "racist thuggery" has no place on UK streets after far-right protests in central London turned violent, resulting in over 100 people being arrested.
Scotland Yard said six of its officers had sustained injuries as the force had imposed restrictions and used search powers to contain the large crowds gathered near Parliament Square, claiming to be out in force to "guard our monuments", on Saturday.
Violent clashes involved protesters hurling bottles, cans and flares towards the Metropolitan Police officers on duty, many in riot gear.
"Racist thuggery has no place on our streets. Anyone attacking the police will be met with full force of the law," said Johnson.
"These marches and protests have been subverted by violence and breach current guidelines. Racism has no part in the UK and we must work together to make that a reality," he said, as thousands ignored the social distancing norms in place to curb the spread of coronavirus.
A further arrest was made on Sunday after footage emerged of a man urinating near a memorial of Police Constable Keith Palmer, who was killed in the 2017 terrorist attack outside the Houses of Parliament.
UK Home Secretary Priti Patel said the "desecration" of the memorial was "utterly shameful".
"We are aware of a disgusting and abhorrent image circulating on social media of a man appearing to urinate on a memorial to PC Palmer," said Met Police Commander Bas Javid.
"I feel for PC Palmer's family, friends and colleagues. We have immediately launched an investigation, and will gather all the evidence available to us and take appropriate action," he said.
The Met Police said it has arrested people for offences including violent disorder, assault on police, possession of an offensive weapon, breach of the peace, being drunk and disorderly and possession of banned Class A drugs.
Separately on Saturday, a number of anti-racism protests also took place in London and around the country, which were largely peaceful. The anti-racism Black Lives Matter protest in London was held at a much smaller scale after the main groups had brought forward its demonstration plans to Friday in order to avoid clashes with right-wing protesters.
Hundreds of protesters were seen gathering around the Cenotaph war memorial in Whitehall and the statue of former UK Prime Minister Winston Churchill in Parliament Square, which was boxed up to protect it from potential damage after protesters wrote "was a racist" on it during last weekend's anti-racism protests.
"Do not destroy our history. Keep our history and learn from it so the same mistakes don't happen again," read a poster on Churchill's boarded-up statue left by protesters.
It came as Churchill's granddaughter, Emma Soames, was asked if her grandfather's statue should be moved to a museum. She told the BBC that if people were "so infuriated" by seeing the statue it may be "safer" in a museum, "but I think Parliament Square would be a poorer place without him."
"He was a powerful, complex man, with infinitely more good than bad in the ledger of his life," she said.
The Met Police had imposed strict conditions on the right-wing rally as well as the anti-racism protests, after fears that the two could end up in a face-off on the streets of London.
Opposition Labour leader, Sir Keir Starmer, said the violence shown towards the police was "completely unacceptable". He said: "The protests in London were led by those intent on causing violence and sowing hate for their own ends. We must not let them win."
The UK has witnessed a series of demonstrations since last week as worldwide protests broke out in the wake of the killing of George Floyd, the African American man who died in police custody in the US.