London’s Metropolitan Police arrested 55 people outside the UK Parliament on Saturday during a protest supporting Palestine Action, a group recently outlawed under anti-terrorism laws.

Demonstrators gathered in Parliament Square holding placards expressing solidarity with the banned group, which was officially proscribed earlier this month. Some signs read, “I oppose genocide, I support Palestine Action.” Many in the crowd wore keffiyehs and were seen being detained and taken away in police vans.

Authorities said the arrests were made due to public displays of support for the organization, now illegal under the Terrorism Act. Police established a “sterile area” to keep the protesters separated from a counter-demonstration organized by “Stop the Hate,” which called for the release of hostages held in Gaza.

Another eight people were arrested at a similar protest in Truro, Cornwall. Demonstrations also took place in Manchester, Bristol, and Edinburgh, organized by the campaign group Defend Our Juries, which openly stated their intention to defy the ban.

The UK government officially designated Palestine Action a terrorist group in early July after its members claimed responsibility for a break-in at a Royal Air Force base, during which they allegedly sprayed red paint on two aircraft, causing an estimated £7 million in damage. Four individuals remain in custody over that incident.

Since the proscription took effect on July 5, British authorities have warned that support for the group is now a criminal offense. Membership alone could result in a prison sentence of up to 14 years.

Palestine Action has called the ban “authoritarian” and plans to challenge it in London’s High Court on Monday. The group has been known for its direct actions against defense contractors and companies linked to Israel amid ongoing conflict in Gaza.

Police have continued to detain supporters across the country in the weeks following the group's proscription. Photo by OwenBlacker, Wikimedia commons.