At least 450 people were arrested at a rally against the proscription of Palestine Action on Saturday outside the UK parliament, police said on Saturday.
Hundreds of demonstrators gathered in support of the direct action group, which was proscribed as a terrorist organisation last month.
Many of them held up placards reading “I oppose genocide. I support Palestine Action” in Parliament Square.
The Metropolitan Police began arresting activists shortly after 12:35pm.
By 9pm, the Metropolitan Police, backed by officers brought in from across the country, confirmed at least 466 arrests for alleged support of a proscribed organisation.
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The scale of detentions appears to surpass the record set during the 1990 poll tax riots, when 339 people were taken into custody.
Met police chief Mark Rowley pledged earlier this week to arrest all participants in the planned protest.
But many holding placards have not been arrested, apparently because the police were unable to detain them all.
The government proscribed the activist group under anti-terror laws on 4 July, following an incident in which members broke into the Royal Air Force Brize Norton base earlier this month and spray-painted two planes they said were “used for military operations in Gaza and across the Middle East”.
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The legislation made membership of and support for the group a criminal offence punishable by up to 14 years in prison – the first time a direct action group has been proscribed in the UK as a terrorist group.
Since then, hundreds of people have been arrested at weekly protests by campaign group Defend Our Juries (DOJ), which said this week that the protests have “changed the meaning” of an arrest under the Terrorism Act and that it is considered a “badge of honour” within the movement.
The group highlighted that the mass arrests could place strain on a prison system already “on the brink of collapse” and remains at 97.5 percent capacity, according to an independent review this week.
‘Disproportionate and unnecessary’
Saturday’s protest comes amid mounting pressure on the UK government to lift the controversial ban amid concerns that it could be used to stifle criticism of Israel and the right to protest.
Last month, UN human rights chief Volker Turk said that the ban was “disproportionate and unnecessary” and called for the designation to be rescinded.
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On Thursday, Amnesty International warned that the mass arrests could break international law, with Amnesty UK Chief Executive Sacha Deshmukh saying: “Arresting people on terrorism offences for peacefully holding a placard flies in the face of international human rights law.
“At a time when people are quite rightly outraged by the genocide they see being perpetrated in Gaza, it is more crucial than ever that there is space to peacefully express that outrage.”
Also on Thursday, scores of leading global academics, including Judith Butler, Tariq Ali, Angela Davis, Naomi Klein, Rashid Khalidi, Avi Shlaim and Ilan Pappe, signed an open letter denouncing Palestine Action’s proscription as an “attack on fundamental freedoms”.
On 30 July, a High Court judge ruled in favour of Palestine Action and granted the direct action group a judicial review to oppose the ban on the group.