But police said no one had been arrested for the attack caught on digital camera that set a police officer on fireplace, AFP reported.

The officer – half of the National Gendarmerie, a nationwide regulation enforcement power that is technically half of the army but under the management of the inside ministry – said his unit “suddenly found ourselves facing several hundred hostile, well equipped adversaries”.

Speaking to French newspaper Le Figaro, he said police were yet to determine the liquid used but that the incendiary gadget “had a far greater burning capacity than a standard Molotov cocktail”.

“We faced hostile individuals who are not protesters,” he said. “These adversaries are there with the intent to harm those who represent the state.”

Fourteen other officers sustained wounds ranging from minor to critical, he said, including some were struck by paving stones. The unit was supposed to be on depart but had been urgently recalled to police the weekend protests, he said.

French protest organisers, the Gilets Jaunes, or Yellow Vests, have said dozens of protesters have been severely injured during current demonstrations across the nation, with many harm by “grenades”.

France suspended the use of one kind of stun grenade while policing scholar protests in early October after a 15-year-old’s hand was blown off, but French newspaper Le Monde has reported that police have continued to use a totally different mannequin in subsequent protests.

Protests also took place in Germany and Italy over the weekend, as primarily youth-led protests proceed across elements of Europe, with various calls for but broadly linked to a focus on cost-of-living points and public providers.