Police in London have detained more than 466 people who were protesting the United Kingdom?s decision to ban the Palestine Action Group, marking the ?largest ever mass arrest? at a single protest in the British capital, according to campaigners.

The arrests came after hundreds of people gathered at Parliament Square in London on Saturday, denouncing Israel?s war on Gaza and holding placards with the message, ?I oppose genocide. I support Palestine Action.?

Videos posted online showed the protesters sitting on the ground, with some chanting, ?Hands off Gaza!? The footage also showed the protesters being carried away by the police as the crowd chanted ?shame on you? at the officers.

The Metropolitan Police, in a statement on X, said that 466 demonstrators had been arrested at Parliament Square by 9pm local time (20:00 GMT) ?for showing support for Palestine Action?. It said eight others were arrested at the protest for other offences, including five assaults on officers.

The group that organised the protest, Defend Our Juries, said on X that some 800 people had held up signs, and that the detention of more than half of the protesters marked ?the largest mass arrest ever by the Met Police at a single protest?.

It added, ?The people are collectively opposing the genocide in Gaza and the Palestine Action ban.?

The protests are the latest in a series of rallies denouncing the UK government?s ban of Palestine Action under the Terrorism Act 2000 in July. The ban came after members of the group broke into a military airbase in June and damaged two planes.

Membership in or support for the group is now a criminal offence punishable by up to 14 years in prison.

Critics say the ban infringes on freedom of speech and the right to protest, as well as aims to stifle demonstrations against Israel?s war on Gaza.

Al Jazeera?s Sonia Gallego, reporting from Parliament Square, said the threat of arrest or punishment ?hasn?t deterred any supporters? of Palestine Action from expressing their backing for the group.

?Something as simple as wearing a t-shirt saying, ?I support Palestine Action?, or even having that written on a sheet of paper?, could lead to an arrest, Gallego said.

?Alternative universe?

Paddy Friend, a protester, told Al Jazeera on Saturday that the mass arrests at Parliament Square raised serious questions about freedoms in the UK.

?If we can?t come down with seven words on a sign and sit quietly, then what does freedom of speech mean?? Friend said.

Another demonstrator, grandmother Manji Mansfield, returned to protest on Saturday, despite having been arrested at a previous rally.

?This isn?t the Britain that I grew up in,? she told Al Jazeera.

?We?re now living in an alternative universe, and I?m not going to accept it.?

John McDonnell, a Labour Party MP, also condemned the arrests. ?It?s a disgrace that people are being arrested for upholding our democratic rights,? he wrote on X.

Amnesty International UK denounced the arrest of peaceful protesters solely for holding signs, saying such action constitutes ?a violation of the UK?s international obligations to protect the rights of freedom of expression and peaceful assembly?.

Palestine Action, which accuses the UK?s government of complicity in what it says are Israeli war crimes in Gaza, has increasingly targeted Israel-linked companies in the country, often spraying red paint, blocking entrances or damaging equipment.

UK Secretary of State for the Home Department Yvette Cooper tabled the order to ban the group in parliament days after its activists broke into RAF Brize Norton, the largest station of the Royal Air Force in Oxfordshire, and sprayed two military planes with red paint, resulting in millions of pounds of criminal damage, according to police.

The ban was passed on July 2.

The move, however, has drawn concern from United Nations human rights exerts, who say labelling Palestine Action as a ?terrorist? group was ?unjustified?, as the group?s actions were limited to civil disobedience and ?mere property damage, without endangering life?.

But Cooper, speaking to reporters on Saturday, insisted that Palestine Action had been outlawed ?based on strong security advice? and following ?an assessment from the Joint Terrorism Assessment Centre that the group prepares for terrorism?.

?Many people may not yet know the reality of this organisation,? she said, claiming the group ?is not non-violent?.

?The right to protest is one we protect fiercely, but this is very different from displaying support for this one specific and narrow, proscribed organisation,? she added.

Repressive consequences

Before the arrests on Saturday, at least 200 people had been detained for protesting the ban.

More than 350 academics from around the world have also signed an open letter, published this week, applauding a ?growing campaign of collective defiance? against Cooper?s decision to proscribe Palestine Action.

The signatories ?deplore the repressive consequences that this ban has already had, and are especially concerned about the likely impact of Cooper?s ban on universities across the UK and beyond?, the letter read.

Israeli historian and University of Exeter professor Ilan Pappe, Goldsmiths, University of London professor Eyal Weizman, and political thinkers Michael Hardt and Jaqueline Rose were among those who signed the letter.

Meanwhile, a separate march organised by the Palestine Coalition group was also held in London on Saturday.

The Metropolitan Police said one person had been arrested at that march, which went from Russell Square to Whitehall, for displaying a banner in support of Palestine Action.

London?s High Court has, meanwhile, ruled that Palestine Action cofounder Huda Ammori can bring a judicial review against the ban, with Judge Martin Chamberlain saying that it was ?reasonably arguable? that proscription amounted to a disproportionate interference with the right to freedom of expression.

However, the full judicial review will not take place until late 2025, according to the lawyers representing Ammori. (Al Jazeera)

Update news