Civil liberties groups have expressed concern after police action against republican protesters attending royal events.

In recent days, a woman was arrested in Edinburgh for holding a cardboard sign containing a swear word and the slogan "abolish monarchy". She has been charged with a breach of the peace.

Her arrest followed an incident in London where a protester was led away by officers after holding up a sign reading, "Not My King". And another in Oxford where a man who shouted "who elected him" at a procession marking King Charles was briefly arrested.

Media reports have also highlighted a barrister who attended a London gathering with a large, blank piece of paper. After suggesting that he might write the words ‘not my king’ on the paper, the officer told him not to do so, or he’d be arrested for causing offence.

Ruth Smeeth, CEO of Index on Censorship, said the incidents are “deeply concerning”, adding: "We must guard against this event being used, by accident or design, to erode in any way the freedom of expression that citizens of this country enjoy."

Whilst Silkie Carlo, of Big Brother Watch, said officers have a “duty to protect people’s right to protest” as much as “facilitate people’s right to express support, sorrow, or pay their respects”.

A spokesman for the Prime Minister told the BBC: "More broadly, obviously, this is a period of national mourning for the majority, the vast majority of the country. But the fundamental right to protest remains as a keystone of our democracy."