Heraldo de Madrid - Anti-monarchists among protesters arrested at UK coronation

Officers from London's Metropolitan Police force detained six organisers from the pressure group and seized hundreds of their placards, Republic said, just hours ahead of Charles's crowning.

Republic chief executive Graham Smith was among those detained near Trafalgar Square before the group had a chance to wave the signs declaring "Not my king".

"They won't tell us why they've arrested them or where they're being held," a Republic activist told AFP at the square.

The Met tweeted that four people were held "on suspicion of conspiracy to cause public nuisance".

"We seized lock-on devices," it added, referring to newly-outlawed contraptions used by demonstrators to attach themselves to each other, an object or the ground.

But the detentions prompted immediate criticism from Human Rights Watch, which called the arrests "incredibly alarming".

"This is something you would expect to see in Moscow, not London," the rights organisation's UK Director, Yasmine Ahmed, said in a statement.

"Peaceful protests allow individuals to hold those in power to account -- something the UK government seems increasingly averse to."

- 'Dystopian' -

The arrests come just days after UK police forces were controversially granted new anti-protest powers by the government following several years of disruptive demonstrations by environmental activists.

It expands protest-related offences to include locking-on and carrying lock-on devices, extends police stop and search powers and allows for new court orders to prevent people from attending demonstrations.

Separately Saturday, at least 19 members of one such environmental campaign group, Just Stop Oil, were also arrested in central London, it said in a statement.

An AFP reporter saw numerous activists being handcuffed by police on The Mall, the processional route from Buckingham Palace to Trafalgar Square.

"Their intention was only to display T-shirts and flags. This is a massive authoritarian overreach," Just Stop Oil said, claiming none of those arrested had "glue, paint or any plans to disrupt the coronation".

"New policing laws mean we're now living in a dystopian nightmare -- this disgraceful over-reach is what you'd expect in Pyongyang, North Korea, not Westminster."

Reports said other protesters were detained, including a man allegedly held in St James's Park for carrying a megaphone.

"It could scare the horses," a police officer at the scene said, according to a Sky News reporter present.

- 'Wrong' -

Republic, which wants the monarch replaced by an elected head of state, had been vocal about its protest plans, but Smith said this week they had no plans to disrupt the procession.

Republic's director Harry Stratton, 30, said activists were carrying placards near Trafalgar Square when around 20 officers stopped and searched them.

"Graham and our volunteers asked why and they said 'we will find that out'," he said. "After that they arrested them saying, 'we are seizing all these placards'."

A camera crew from the group Alliance of European Republican Movements present asked a senior police officer why they were being held.

"They're under arrest. End of," the officer replied, according to footage posted on Twitter.

The Met, which had this week vowed "low tolerance for any disruption", tweeted that officers made "a number of arrests" as part of its "significant police operation".

Dubbed "Golden Orb", it deployed 11,500 officers on Saturday and facial-recognition technology which civil liberties organisations branded "authoritarian".

The detentions left the scores of other demonstrators -- who rallied near The Mall as well as in Trafalgar Square -- incensed.

M.Soler--HdM