Michel Forst, the UN special rapporteur on environmental defenders, said he had received "extremely worrying information" during a recent visit to Britain about "an increasingly severe crackdown".

"Regressive laws" were being used to slap environmental and climate activists with severe penalties, "including in relation to the exercise of the right to peaceful protest", he warned in a statement.

Forst, an independent expert appointed by the UN Human Rights Council but who does not speak on behalf of the United Nations, stressed that "the right to protest is a basic human right".

"It is also an essential part of a healthy democracy," he said.

British police were controversially granted anti-protest powers by the government last year following several years of disruptive demonstrations by environment activists.

Forst said peaceful demonstrators are being prosecuted under the 2022 Police, Crime, Sentencing and Courts Act for the criminal offence of "public nuisance", punishable by up to 10 years behind bars.

In addition, the 2023 Public Order Act is being used "to further criminalise peaceful protest", he said.

Last month, for instance, a peaceful climate protester who took part in an approximately 30-minute slow march on a public road was sentenced to six months in prison.

'Toxic discourse' 
 

Forst stressed it had hitherto been "almost unheard of since the 1930s for members of the public to be imprisoned for peaceful protest in the UK".

The expert also said it was incomprehensible that some judges were barring "environmental defenders from explaining to the jury their motivation" for protesting "or from mentioning climate change at all".

He voiced alarm at harsh bail conditions slapped on environmental protesters while they await trial, including bans on further protests or having contact with others in their movement.

Some activists were also required to wear electronic ankle tags or GPS trackers.

Currently, "environmental defenders may be on bail for up to two years from the date of arrest to their eventual criminal trial," he said.

Forst said environmental activists were frequently publicly derided in British media and by politicians, placing them at heightened risk of threats, abuse and physical attacks.

This "toxic discourse", he warned, "may also be used by the state as justification for adopting increasingly severe and draconian measures against environmental defenders".

"We are in the midst of a triple planetary crisis of climate change, biodiversity loss and pollution. Environmental defenders are acting for the benefit of us all," Forst said.

A spokeswoman for Britain's Home Office told AFP: "The right to protest is a fundamental part of our democracy but we must also protect the law-abiding majority's right to go about their daily lives.

"While decisions on custodial sentences are a matter for the independent judiciary, the Public Order Act brings in new criminal offences and proper penalties for selfish, guerrilla protest tactics," the interior ministry added.