French prosecutors have opened an investigation into an instance of intentional violence after a video went viral of a riot police officer brutally punching an already-wounded protester detained at a rally in Paris.

The footage, which was filmed during a ‘Yellow Vest’ rally on Saturday, showed the helmeted officer holding a man with a bloodied head down on his back and repeatedly punching him in the face.

The incident was also caught on camera from another angle. In the second video, the injured man is seen on his stomach screaming in pain as the officer pins down his elbow with his knee.

The videos were widely shared on social media platforms, renewing criticisms of police brutality during the 16-month protests.

Amid the outcry, Paris prosecutor office ordered an investigation into intentional violence by a person in a position of public authority.

The Paris police department also reacted to the footage, calling on the department of public order to give a full account of this incident.

The violence occurred near the Gare de l’Est train station as the ‘Yellow Vest’ protesters returned to the streets of the capital as part of the weekly demonstrations they have been holding since November 2018 against the economic policies of President Emmanuel Macron.

The ‘Yellow Vest’ movement has been boosted by a separate wave of protests and strikes against a planned overhaul of pensions, which have affected public transportation, disrupted schools, hospitals, courthouses and even opera houses and the Eiffel tower over the past weeks.

There have been several cases of police brutality in the course of the protests, including the death of a man during an arrest operation in Paris and the use of rubber bullets against pension reform protesters.

Macron and his ministers had long rejected reports of police brutality, defending the police force as a victim of sustained attacks by anti-government protesters.

Paris was, however, forced to change its tone as several new cases of police violence emerged, piling more pressure on the government.

Macron warned earlier this month that the unacceptable behavior of some officers risked undermining the credibility and dignity of the force.

On January 3, a 42-year-old delivery man died of suffocation after being pinned face down on the ground during an arrest operation in Paris. A week later, a video showed another man falling to the ground after an officer apparently fired rubber bullets at point-blank range into a group of pension protesters.

The Council of Europe urged France in February 2019 to suspend the use of rubber bullets against demonstrators. A month later, the UN human rights chief called for a thorough investigation into reports of excessive police force in the European country.