More than 210,000 people have joined protests in the UK following the killing of George Floyd, the home secretary has said.
Priti Patel told MPs that 160 demonstrations were held over the weekend, with the “vast majority” passing peacefully.
But she condemned “ugly scenes” in Westminster, where an estimated 2,000 football hooligans, far-right protesters and veterans rallied to “defend” monuments on Saturday.
“Many of the so-called protesters came with the deliberate intent of harming those around them and police officers,” Ms Patel said, calling their actions “indefensible”.
“Those thugs, far from protecting our heritage, did all that they could to destroy and undermine those values. There is no place for their sickening conduct and hate in our society.
“They were violent, they were aggressive and abusive towards police officers. They were patently racist.”
Ms Patel said that Saturday saw 137 arrests for offences including assaulting police, violent disorder, breaches of the peace, possession of offensive weapons and class A drugs.
The home secretary hit out at “senseless violence” throughout the day, adding: “It’s clear that the far-right thugs that descended on London this weekend shamed themselves.”
She called far-right extremism a “serious and growing threat” to the UK and added: “We have to be vigilant to protect our people, our country, but also to prevent some terrible atrocity from taking place.”
She called the photo of a man urinating next to the memorial to PC Keith Palmer the “most abhorrent” image of the day.
Andrew Banks, 28, was jailed for two weeks for outraging public decency at Westminster Magistrates' Court earlier on Monday.
Another protester admitted kicking a police officer in the back at the same demonstration on Saturday, after being identified by his lime green shorts.
Daniel John Allan, a 35-year-old from Sunderland, will be sentenced at a later date.
At least 38 police officers were hurt this weekend, Ms Patel said, while in total around 100 officers, three horses and one police dog have been injured in all protests since Mr Floyd’s death.
So far, 280 arrests have been made across England and Wales.
Ms Patel said the government is considering “all options” to respond to the desecration of memorials, which have also been vandalised during previous Black Lives Matter protests.
“I refuse to allow monuments to heroes who served their country to be vandalised and desecrated,” she told the House of Commons.
“This government is considering all options to stop those who seek to attack these emblems of our national sacrifice and pride, including the proposed Desecration of War Memorials Bill.“
Shadow home secretary Nick Thomas-Symonds said Labour would scrutinise government proposals, and pointed out that criminal damage could already be punished by 10 years’ imprisonment.
He added: "There should be no attempt to draw comparisons between those intent on violence this weekend and the legitimate cause of the Black Lives Matter campaigners, who have brought attention to the impact that racism and inequality continues to have both here in the UK and across the world. Now is the time for action."