Police in London arrested 139 people during a demonstration outside the U.S. Embassy on Saturday over their support for Palestine Action, a group banned by the UK government under anti-terrorism laws.
Most of those arrested were detained for expressing support for a proscribed organisation, London's Metropolitan Police said in a statement. Officers remained at the scene, with further arrests expected, it added.
Many demonstrators were elderly people carrying placards reading, "I oppose genocide, I support Palestine Action." One protester climbed a tree outside the embassy, holding a sign that read, "God help us. Teachers who support Palestine. Palestine Action."
According to Defend Our Juries, the activist group behind the demonstration, more than 4,000 people have been arrested since July 2025 for protesting against the ban.
The group described the arrests as "dystopian", arguing that anti-terrorism laws were being used against peaceful demonstrations expressing opposition to genocide and support for Palestine Action.
The UK government designated Palestine Action a terrorist organisation last year. Under the ban, membership of or support for the group is a criminal offence carrying a maximum prison sentence of 14 years.
A similar vigil was held outside the U.S. Consulate in Edinburgh, Scotland, where demonstrators displayed placards supporting Palestine Action. No arrests were reported. However, Police Scotland said it was investigating people seen wearing T-shirts and carrying banners in support of the banned organisation.
"Evidence is being reviewed and further action will be taken as appropriate," the force said.
The demonstrations came ahead of a Supreme Court appeal scheduled for November 4 challenging the government's decision to designate Palestine Action as a terrorist group. Supporters argue that the ban is excessive and violates freedom of expression.
In August, the U.S. government also imposed sanctions on Palestine Action, designating it as a terrorist organisation.
Founded in 2020, Palestine Action campaigns against British military support for Israel, accusing the country of committing genocide against Palestinians. Israel strongly rejects the allegation.
The group says it seeks to prevent genocide by disrupting companies it considers part of Israel's military-industrial network.
In 2024, its activists broke into a factory belonging to Israeli arms manufacturer Elbit Systems UK, damaging equipment with sledgehammers and crowbars. In June 2025, members also entered a Royal Air Force base, sprayed red paint into the engines of two tanker aircraft and caused additional damage using crowbars.