“Not my king” protesters take to the streets of London as King Charles III is crowned on Saturday. James Forde/The Washington Post

LONDON — Human rights groups and politicians in Britain are criticizing the law enforcement response to King Charles III’s coronation after Metropolitan Police arrested dozens of demonstrators during Saturday’s pageantry.

Republic, an anti-monarchy group that organized a protest in central London during the coronation, said police arrested six of its members, including leader Graham Smith, and seized hundreds of placards even before its event began.

Smith, who said he was released from police custody later that day, declared “there is no longer a right to peaceful protest in the U.K.” He added, “I have been told many times the monarch is there to defend our freedoms. Now our freedoms are under attack in his name.”

Yasmine Ahmed, the U.K. director of Human Rights Watch, was quoted by the Guardian newspaper as calling “the reports of people being arrested for peacefully protesting [against] the coronation … incredibly alarming.”

“These are scenes you’d expect to see in Russia not the UK,” she tweeted.

The arrests came as the Met, as the police force for Greater London is known, warned of its “significant police operation” for the day. Three people were arrested near Buckingham Palace and “held on suspicion of possessing articles to cause criminal damage,” officials said.

It’s unclear how many of the arrests, if any, were on suspicion of violating the Public Order Act, a controversial bill that became law days before the coronation and gave authorities new powers to restrict protests. The Met did not respond to a request for comment Sunday.

Met Commander Karen Findlay said in a statement Saturday that 52 arrests were made for “offenses including affray, public order offenses, breach of the peace and conspiracy to cause a public nuisance. All of these people remain in custody.”

“We absolutely understand public concern” about the arrests, Findlay acknowledged. But she added, repeating a position the police laid out last week that sparked a backlash among rights groups, “we said our tolerance for any disruption, whether through protest or otherwise, will be low and that we would deal robustly with anyone intent on undermining the celebration.”

Protestors wait for the arrival of King Charles III and Queen Camilla in Liverpool on April 26. Jon Super/Pool via Associated Press file

Hundreds of people had gathered at Trafalgar Square – within view of the king’s procession to and from Westminster Abbey – to call for the monarchy to be abolished and replaced by an elected head of state. The protesters stood for hours amid rain, holding placards that poked fun at the royal family and criticized the expense of a coronation amid a cost-of-living crisis. Many chanted slogans like “not my king” or “down with the crown.”

Members of the Republic told The Washington Post they had conversations with the Metropolitan Police ahead of their demonstration to avoid any misunderstandings and reduce the risks of a police response. But even before the protest had officially begun, officers arrested Smith and five other members and seized a van containing the group’s placards, according to Harry Stratton of Republic.

In the United Kingdom, an arrest is more akin to detention in the United States, though individuals who are then charged must appear before a judge.

The Met declined to confirm Smith’s arrest, but it said in a statement that six people were arrested near Trafalgar Square “on suspicion of conspiracy to cause a public nuisance.” In making Saturday’s arrests, Findlay said officers had acted on “information that individuals would attempt to deface public monuments with paint, breach barriers and disrupt the official movements.”

Its statement did not specify how many of the 52 people arrested would be charged with a crime.

Ahead of his detention, Smith told The Post that Charles’ accession to the throne was a turning point for the Republican movement – those who advocate for Britain to become a republic. “Things are changing already,” he said. “People are no longer worried about criticizing, challenging, and speaking up about being a Republican.”

Separately, the climate change group Just Stop Oil said in a statement that some of its supporters were also arrested during Saturday’s coronation.

“During this morning’s coronation celebrations, around 20 supporters were arrested wearing Just Stop Oil T-shirts. No disruptive action was planned, the supporters were not intending to jump the barrier, merely reveal their T-shirts and hold flags emblazoned with ‘Just Stop Oil,'” the statement said.

Saturday’s gatherings were the first test of the Public Order Act, which has prompted concerns from rights groups about diminishing protections for free speech and the freedom to protest. The law severely restricts protest tactics deemed to be particularly disruptive. It is now a crime, punishable by up to six months in prison and/or an unlimited fine, for protesters to attach themselves to “others, objects or buildings to cause serious disruption.”

The bill also authorizes police under certain circumstances to stop and search protesters for items that could be used to commit a protest-related offense “without the need for suspicion” that the protesters intend to commit an offense, according to the government.

The U.N. high commissioner for human rights, Volker Turk, said the law “imposes serious and undue restrictions” on people’s rights to speak, assemble and associate freely “that are neither necessary nor proportionate to achieve a legitimate purpose as defined under international law.”

Saturday’s coronation arrests also prompted criticism from British politicians. Jess Phillips, a member of Parliament for the Labour Party and opposition spokesperson for home affairs, tweeted: “our nation and our King is not so fragile as to not be able to take harmless protest of a different view.”

Labour lawmaker Zarah Sultana called the arrests of the Republic protest organizers “deeply disturbing.”

“Whatever you think of the monarchy, the right to peaceful protest is fundamental to democracy,” she said. “This is a chilling violation of that right.”