Fifty-five people were arrested at an anti-Israel, pro-Palestinian rally outside Britain’s parliament on Saturday, for alleged support for the banned Palestine Action group, London’s Metropolitan Police said.

The crowd in Parliament Square had been waving placards supporting the group that was banned this month under anti-terrorism legislation, the force said in a post on X.

People from the rally, some wearing keffiyehs, were taken away in police vans.

At the protest, demonstrators held signs reading “I oppose genocide, I support Palestine Action.”

Police said that they created a “sterile area” to prevent the anti-Israel, pro-Palestinian marchers from reaching the Stop the Hate counter-protest, calling for the hostages held in Gaza to be released.

A further eight demonstrators were held in Truro in Cornwall.

Other protests were held in northwestern Manchester, western Bristol and the Scottish capital Edinburgh.

Saturday’s rallies were organized by campaign group Defend Our Juries which had said they were intended to “defy” the ban.

Palestine Action’s proscription was approved by parliament in the first days of July, and a last-ditch High Court challenge failed to stop it from becoming law.

The government announced plans for the ban under the Terrorism Act days after the group’s activists claimed responsibility for a break-in at an air force base in southern England.

The group said it sprayed two aircraft with red paint, causing an estimated £7 million ($9.55 million) in damage.

Four people charged in the incident remain in custody

Since the ban came into effect on July 5, police have warned that expressing support for Palestine Action is now a crime, and membership in the group now carries a prison sentence of up to 14 years.

The group has called the decision “authoritarian,” and a challenge to the ban will be heard at London’s High Court on Monday.

Palestine Action is among groups that have regularly targeted defense firms and other companies in Britain linked to Israel since the start of the conflict in Gaza.

Police have arrested scores of the group’s supporters at rallies across Britain since the ban came into force earlier this month.