MPs and human rights groups have criticized the Metropolitan Police after 52 people were arrested on Coronation Day in London.
Among those arrested was the head of the group Republic, which wants to abolish the monarchy and elect a head of state.
Graham Smith, who was released on Saturday evening after 16 hours in custody, said there was “no longer a right to peaceful protest in Britain”.
Scotland Yard said it had acted “proportionately”.
Commander Karen Findlay defended her officers’ response to the Coronation Day protests, saying they had a duty to intervene “when protests become criminal and cause serious disruption”.
He added that the coronation was “a once-in-a-generation event and is a key consideration in our assessment”.
Hundreds of protesters gathered in the rain in central London on Saturday, chanting “down with the crown”, “don’t talk to the police” and “get a real job”.
Other demonstrations were organized in Cardiff, Glasgow and Edinburgh. No arrests were reported outside London.
Scotland Yard said those arrested are being held on suspicion of sedition, public order offences, breach of the peace and conspiracy to cause public disturbance around the coronation.
While campaigners insisted their protest was peaceful, police said they had intelligence that groups were “determined to spoil” the occasion.
Several Labor MPs criticized the Met’s response, with senior backbencher Sir Chris Bryant writing on Twitter that “free speech is the silver thread that runs through the parliamentary constitutional monarchy”.
Shadow minister Jess Phillips also took to social media to say that “our nation and our monarch are not too fragile to protest a different point of view harmlessly”.
Labor MP Richard Burgon said he was “deeply concerned” by the arrests, while MP Zara Sultana said: “Whatever you think about the monarchy, the right to peaceful protest is fundamental to democracy. “
Among those criticizing the Met was Human Rights Watch’s UK director, Yasmin Ahmed, who likened its actions to “something you would expect to see in Moscow, not London”.
Mr Smith confirmed that he had been released late on Saturday evening, adding that other members of the republic were still in custody.
Writing on Twitter, he said “there is no longer a right to peaceful protest in the UK”.
“I have been told many times that the King is there to defend our freedoms. Now our freedoms are being attacked in his name.”
Mr Smith was arrested earlier on Saturday – before the coronation began – during a protest in Trafalgar Square.
Footage from the day showed a number of protesters wearing “Not My King” T-shirts being detained – including Mr Smith.
The Republic also said that police had confiscated hundreds of its placards.
