LONDON — Lawyers acting for Palestine Action pressed their legal challenge against the British government's ban on the group on Friday, days after the United States designated it a terrorist organisation and imposed sanctions on its associates. The case continued at the High Court in London.

The US State Department announced on Wednesday that it had designated Palestine Action, alongside two other groups, accusing them of supporting terrorism. Britain proscribed the group in 2025 under the Terrorism Act 2000, making membership or support a criminal offence carrying lengthy prison sentences.

The co-founder of Palestine Action, Huda Ammori, has sought a judicial review of the proscription, arguing it criminalises legitimate protest against arms companies. Her legal team, instructed through the firm Bindmans, contends that the ban is a disproportionate interference with rights to free expression and assembly under the European Convention on Human Rights.

Civil liberties organisations including Amnesty International UK and Liberty have criticised the proscription, warning it sets a precedent for treating direct-action protest as terrorism. Home Office officials have defended the designation, saying the group's activities crossed the threshold set out in counter-terrorism legislation.

The coordinated pressure from Washington and London reflects a hardening of Western policy toward pro-Palestinian activist networks. Hundreds of people have been arrested at demonstrations across Britain for displaying signs supporting the banned group since the ban took effect.