LONDON - British police have been reminded by their commanders of the people's "right to protest", after a video emerged of officers escorting an anti-monarchy protester away from Parliament.

"The public absolutely have a right to protest," Metropolitan Police Deputy Assistant Commissioner Stuart Cundy said in a statement. "We have been making this clear to all officers involved in the extraordinary policing operation currently in place, and we will continue to do so."

Mr Cundy said the "overwhelming majority of interactions" between officers and people have been "positive", as crowds turn out in central London and other places to pay their respects after the death of Queen Elizabeth.

His statement late Monday followed a viral footage of a female protester, holding aloft a "not my king" protest placard, being confronted by at least four officers outside Parliament in London. She was seen being escorted away from the spot, and was reportedly made to stand at another location away from the gates of Parliament.

A witness told British media that she was not arrested and was allowed to continue her protest Monday.

Earlier, the woman and another anti-royal demonstrator were booed by crowds opposite Parliament, as King Charles made his maiden address to lawmakers inside.

The pair held aloft signs saying "End feudalism", "Abolish the monarchy" and "Not my king".

"He's a king without consent, and that's not right," she told reporters.

Meanwhile, it has been reported that another woman who held an "abolish monarchy" sign at a proclamation ceremony for King Charles in Edinburgh on Sunday has been charged with a criminal offence.

Civil rights group Big Brother Watch hit out at the police handling of the protests. "If people are being arrested simply for holding protest placards, then it is an affront to democracy and highly likely to be unlawful," it said.

"Police officers have a duty to protect people's right to protest as much as they have a duty to facilitate people's right to express support, sorrow, or pay their respects," the group added. AFP