Police arrested almost 900 people at a demonstration in support of Palestine Action in the United Kingdom, in the latest round of detentions of its supporters since the pro-Palestinian group was banned by the government as a “terrorist” organisation.

Police arrested 857 people for showing support for a proscribed group, while 33 people were arrested for other offences, including 17 for assaults on police officers, the Metropolitan police said on Sunday.

Defend Our Juries, the organising campaign, estimated 1,500 people joined the London demonstration on Saturday, assembling with placards stating “I oppose genocide, I support Palestine Action”.

Police immediately began detentions while crowds chanted “Shame on you” and “Met Police, pick a side, justice or genocide”. Confrontations intensified as officers removed nonresistant protesters who became passive during arrest.

Following the eight-hour protest, authorities confirmed on Saturday more than 425 arrests, with at least 25 people facing charges of assaulting officers or public order violations, while the remainder were held under the Terrorism Act. Those figures jumped two-fold with new police figures on Sunday.

The UK-based PA Media reported that police drew their batons during the clashes, and one protester was seen with blood streaming down his face behind a barrier after being arrested.

The agency also reported that police had screaming arguments with demonstrators and had water and plastic bottles thrown at them while several protesters fell over in a crush at one point.

Deputy Assistant Commissioner Claire Smart said, “In carrying out their duties today, our officers have been punched, kicked, spat on, and had objects thrown at them by protesters.” She described the treatment as “intolerable”.

Defend Our Juries disputed the narrative, asserting that police initiated the aggression and calling claims of protester violence “frankly laughable”.

Earlier, related demonstrations had resulted in more than 700 arrests, of which 138 individuals were charged under the Terrorism Act.

Mike Higgins, a 62-year-old blind wheelchair user previously arrested at a protest, returned to demonstrate on Saturday.

“And I’m a terrorist? That’s the joke of it,” he said. “I’ve already been arrested under the Terrorism Act, and I suspect I will be today.

“Of course I’ll keep coming back. What choice do I have?”

The United Nations human rights chief has criticised the British government’s approach, stating the new law “misuses the gravity and impact of terrorism”.

The classification of Palestine Action as a terrorist organisation “raises serious concerns that counterterrorism laws are being applied to conduct that is not terrorist in nature, and risks hindering the legitimate exercise of fundamental freedoms across the UK”, Volker Turk warned.

He further noted that by international standards, “terrorist” acts should be limited to crimes such as those intended to cause death or serious injury or the taking of hostages.

Huda Ammori, Palestine Action’s cofounder, denounced the government’s ban as “catastrophic” for civil liberties, creating a “much wider chilling effect on freedom of speech”.

The organisation has received support from notable cultural figures, including bestselling Irish author Sally Rooney, who stated she planned to use the proceeds of her work “to keep backing Palestine Action and direct action against genocide”.

Israel strongly rejects accusations of committing genocide, though numerous countries, rights groups and scholars have confirmed it is carrying out a clear and systematic genocide of Palestinians in Gaza.

The government emphasised that designating Palestine Action as a “terrorist” group does not impact other lawful organisations — including pro-Palestinian or pro-Israel voices — campaigning or peacefully protesting.

A separate pro-Palestinian march in London on Saturday attracted approximately 20,000 participants, according to police estimates.