“As of 9pm, 466 people had been arrested for showing support for Palestine Action,” the Metropolitan Police wrote on X on Saturday.

Parliament in early July passed a law banning Palestine Action and making it a crime to publicly support the organisation.

Supporters of the group are challenging the ban in court, saying the government has gone too far in declaring Palestine Action a terrorist organisation.

“Once the meaning of ‘terrorism’ is separated from campaigns of violence against a civilian population, and extended to include those causing economic damage or embarrassment to the rich, the powerful and the criminal, then the right to freedom of expression has no meaning and democracy is dead,” Defend Our Juries said on its website.

The arrests outside Parliament came amid what is expected to be a busy weekend of demonstrations in London as the war in Gaza and concerns about immigration spur protests and counterprotests across the United Kingdom.

While Prime Minister Keir Starmer has angered Israel with plans to recognise a Palestinian state later this year, many Palestinian supporters in Britain criticise the government for not doing enough to end the war in Gaza.

Pro-Palestinian protesters gathered on Saturday afternoon in central London for a march that ended outside the gates of No. 10 Downing Street, the prime minister’s official residence and offices.

On Sunday, a number of groups are scheduled to march through central London to demand the safe release of the Israeli hostages in Gaza. Palestinian militants have held the captives since Hamas-led attackers surged into Israel on October 7, 2023, killing around 1200 people and taking 251 hostage. There are 50 remaining hostages, with 20 of them thought to be alive.

Police are also preparing for protests outside hotels across the country that are being used to house asylum-seekers. Protesters and counter-protesters have squared off outside the hotels in recent weeks, with some saying the migrants pose a risk to their communities and others decrying anti-immigrant racism.

Deputy Assistant Commissioner Ade Adelekan said the scale of the events would “put pressure” on the police department.

“This is going to be a particularly busy few days in London with many simultaneous protests and events that will require a significant policing presence,” Adelekan said before the protests began.