London — Police in London have arrested hundreds of protesters demonstrating in support of Palestine Action, a group designated as a “terror organisation” by the UK government last month.

According to the Metropolitan Police, 466 people were detained at Parliament Square by 9 p.m. local time on Saturday for “showing support for Palestine Action.” Earlier, the police warned via X that they would arrest anyone expressing such support.

Videos on social media showed officers removing protesters seated in the square, holding signs reading, “I oppose genocide. I support Palestine Action.” Organisers from Defend Our Juries described the gathering as a collective stand against “genocide in Gaza” and the ban on Palestine Action.

Critics argue the government’s decision under the Terrorism Act 2000 — making membership or support for Palestine Action punishable by up to 14 years in prison — infringes on free speech and the right to protest. Even wearing a T-shirt or holding a sign with “I support Palestine Action” could result in arrest.

Since the ban took effect in July, more than 200 people have already been arrested during protests across the UK. Over 350 academics worldwide have signed an open letter praising a “campaign of collective defiance” against Home Secretary Yvette Cooper’s decision, warning of its repressive effects, particularly on universities. Signatories include Israeli historian Ilan Pappe, Professor Eyal Weizman, and political theorists Michael Hardt and Jacqueline Rose.

On the same day, a separate march by the Palestine Coalition took place in London, where one person was arrested for displaying a pro-Palestine Action banner.

Amnesty International UK condemned the arrests of peaceful demonstrators holding signs, calling it a breach of the UK’s obligations to uphold freedom of expression and peaceful assembly.