At least 26 protesters arrested ahead of Charles' coronation in London

British police early Saturday arrested at least 26 anti-monarchy protesters and environmental activists in central London ahead of the coronation of Britain's King Charles III.

The arrests came hours before the historic event, in which the UK was about to witness the first coronation of a monarch in nearly 70 years. Six Republic protesters, including Graham Smith, the chief executive of the group, were arrested, it said on Twitter.

Republic had long before announced that they would hold "Not My King" protest at the Trafalgar Square in central London on the coronation day.

The Alliance of European Republican Movements (AERM) shared on Twitter that police also seized hundreds of signs reading "Not My King."

In response to a question by the AERM, police confirmed the arrests but gave no further details.

"This morning, @GrahamSmith_ and 5 members of our team were arrested. Hundreds of placards were seized. Is this democracy?" Republic also said on Twitter.

On early Saturday, Republic, known as the leading anti-monarchy group in the UK, wrote on social media: "Instead of a coronation we want an election. Instead of Charles we want a choice. It's that simple."

Anti-monarchy protesters held a demonstration at the Trafalgar Square with the attendance of a large crowd.

'Living in a dystopian nightmare'

Meanwhile, the Just Stop Oil group said that 20 environmental activists were arrested by police.

"No supporters of Just Stop Oil arrested in the crowd had glue, paint or any plans to disrupt the Coronation," the group said on Twitter.

New policing laws mean "we're now living in a dystopian nightmare," it added.

In the country's first coronation service in nearly 70 years, Britain's King Charles III on Saturday was crowned along with Queen Camilla at Westminster Abbey, the site of coronations in Britain since 1066 – nearly a millennium ago.

Following the coronation service conducted by the archbishop of Canterbury, the senior bishop of the Church of England, Charles was crowned with the historical St. Edward's Crown, while Queen Camilla wore a modified version of the Crown of Queen Mary, fashioned in 1911.

Charles ascended the throne on Sept. 8, 2022, following the death of his long-serving mother Queen Elizabeth II.

He is the 40th British monarch to take the traditional Oath of Faithful Service.