LONDON (AP) — An anti-monarchy group says it plans to take legal action against London’s Metropolitan Police after several of its members were arrested as they prepared to protest the coronation of King Charles III.

Civil liberties groups are accusing the police, and Britain’s Conservative government, of stifling the right to protest with new powers to clamp down on peaceful but disruptive demonstrations.

The police force expressed “regret” late Monday that the activists were prevented from protesting, but defended its handling of the coronation, which drew hundreds of thousands of people into the streets of London — hundreds of protesters among them.

Police arrested 64 people around Saturday’s coronation, most for allegedly planning to disrupt the ceremonies. Four have been charged, most have been released on bail, and six members of anti-monarchist group Republic have been freed and told they will not face any charges.

Republic chief executive Graham Smith said three senior police officers had come to his house and apologised in person for the arrest that saw him held in custody for 16 hours.

“I said for the record I won’t accept the apology,” Smith said, adding that the group “will be taking action.”

The UK’s recently passed Public Order Act, introduced in response to civil disobedience by environmental groups, allows police to search demonstrators for items including locks and glue and imposes penalties of up to 12 months in prison for protesters who block roads or interfere with “national infrastructure.”

Police said the Republic members had items that could be used to “lock on” to infrastructure. Republic said the items were ties for their placards and police acknowledged its “investigation has been unable to prove intent to use them to lock on and disrupt the event.”

“We regret that those six people arrested were unable to join the wider group of protesters in Trafalgar Square and elsewhere on the procession route,” police said.

The Conservative government defended police handling of the protests, London Mayor Sadiq Khan, a member of the Labour Party, requested “further clarity” from the force. He said the right to peaceful protest is an integral part of democracy.

Conservative lawmaker David Davis said the new powers of arrest were too broad.

“No-one wants a day ruined, but the right to put up placards is virtually absolute in British democracy,” he told the BBC on Tuesday.

The Metropolitan Police force is already under intense pressure after a series of scandals involving its treatment of women and minorities. Confidence in the force plummeted after a serving officer raped and killed a young woman in London in 2020.

An independent review commissioned after the murder said the force was riddled with racism, misogyny and homophobia.