UK police have announced that 325 demonstrators were arrested at a pro-Palestinian protest rally outside the US embassy in London.

British demonstrators had staged the “mass action” in support of Palestinians outside the US embassy on Saturday.

The pro-Palestinian rally took place ahead of a Supreme Court hearing on the proscription of Palestine Action, a proscribed group under a 2025 anti-terrorism legislation.

Police claimed the protesters at the demonstration rally had expressed support for Palestine Action.  The United States has also labeled the Palestine Action organization as a “terrorist” group.

US sanctions Palestine Action, designates group as 'terrorist organization'

The Trump administration has frozen the activist group’s assets and barred Americans from providing funds, goods or services to it.

“In total, 325 people were arrested yesterday,” London’s Metropolitan Police said in an update on Sunday. “The vast majority of arrests — 320 — were for expressing support for a proscribed organization under the Terrorism Act.”

Since British lawmakers proscribed Palestine Action in July 2025, some 4,000 demonstrators have been arrested by the UK police so far.

Many of the arrested people at the pro-Palestinian rallies are elderly people who are strongly opposed to the ongoing Israeli genocidal war against Palestinians in the Gaza Strip, which has continued since October 2023, leaving more than 74,000 people, mostly women and children, killed.

During Saturday's rally, protesters carried placards with slogans such as "We are protesters, not terrorists" and "How is trying to stop a genocide a crime?"

Under the UK Terrorism Act 2000, membership or support of a proscribed group is deemed a crime that’s punishable by up to 14 years in prison.

In the meantime, the proscription of the Palestine Action group remains in effect in the UK following a June 2026 Court of Appeal ruling.

The Supreme Court will start a two-day hearing on the Court of Appeal ruling on Wednesday.