“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.

Backers of the group, who have held a series of protests around the UK over the past month, argue that the law illegally restricts freedom of expression.

Daring police to arrest them

More than 500 protesters filled the square outside the Houses of Parliament on Saturday, many daring police to arrest them by displaying signs reading “I oppose genocide. I support Palestine Action”.

That was enough for police to step in.

But as the demonstration began to wind down, police and protest organisers sparred over the number of arrests as the organisers sought to show that the law was unworkable.

“The police have only been able to arrest a fraction of those supposedly committing ‘terrorism’ offences, and most of those have been given street bail and allowed to go home,” Defend Our Juries, which organised the protest, said in a statement.

“This is a major embarrassment to (the government), further undermining the credibility of this widely ridiculed law, brought in to punish those exposing the government’s own crimes.”

London’s Metropolitan Police Service quickly hit back, saying this wasn’t true and that many of those who gathered in the square were onlookers, media or people who didn’t hold placards supporting the group.

“We are confident that anyone who came to Parliament Square today to hold a placard expressing support for Palestine Action was either arrested or is in the process of being arrested,” the police force said in a statement.

On Friday, police said the demonstration was unusual in that the protesters wanted to be arrested in large numbers so as to place a strain on police and the broader criminal justice system.

Why the group is being banned

The government moved to ban Palestine Action after the activists broke into a British air force base in southern England on June 20 to protest British military support for the Israel-Hamas war. T

he activists sprayed red paint into the engines of two tanker planes at the RAF Brize Norton base in Oxfordshire and caused further damage with crowbars.

Palestine Action had previously targeted Israeli defence contractors and other sites in the United Kingdom that they believe have links with the Israeli military.

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.