More than 500 people were arrested on Saturday during a demonstration against the ban on Palestine Action in central London, the Metropolitan Police said, according to the BBC.
The force said it had made the arrests when people showed support for a proscribed organization. The age of those arrested ranged from 18 to 87, police said.
Hundreds gathered in Trafalgar Square, with many carrying signs in support of the group reading "I oppose genocide. I support Palestine Action", which have been seen at previous protests organised by the group.
Saturday's protest, named Everyone Day, had been called by Defend our Juries, who said the event would demonstrate the "unwaning resistance to the ban on Palestine Action".
Placards with other slogans were also displayed, with some demonstrators declaring their support for defending the right to protest and displaying their opposition to the US and Israel.
Palestine Action was proscribed in July of 2025 after what authorities described as an escalation in “direct action" targeting Israel-linked defense companies in Britain. Activists have frequently blocked entrances to facilities and sprayed red paint during protests.
The ban followed a June break-in at the Royal Air Force base at Brize Norton, during which activists damaged two aircraft. Prime Minister Keir Starmer described the incident as “disgraceful".
In February, the High Court in London ruled that the ban was unlawful, determining that it amounted to a disproportionate interference with free speech rights. However, the ban remains in place pending as the British government has been granted permission to appeal it.
Ahead of Saturday's demonstration, the Met Police issued a statement warning of "criminal offenses", and urging people to reflect on the "potential consequences" of attending.
Some of those attending the demonstration told the BBC they were willing to run the risk of arrest.
More than 2,200 people have been arrested so far for allegedly expressing support for Palestine Action since it was banned under the Terrorism Act 2000 last summer by then-Home Secretary Yvette Cooper.
The trials of hundreds of people accused of holding up the placards have been put on hold while the legal battle over whether the group should have been banned continues.
Palestine Action describes itself as a “direct action" network opposing what it calls British “complicity" with Israel, particularly in relation to arms sales.
The group also previously defaced a painting of Lord Balfour at Trinity College Cambridge, spraying the portrait with red paint and slashing it.
In another incident, Palestine Action members stole two busts of Israel’s first President, Chaim Weizmann, from a glass cabinet at Manchester University.