After receiving a criminal complaint from the family, French prosecutors announced on Wednesday that they were looking into the case of a man who was gravely injured during a protest over access to water.

After Saturday's massive environmental demonstration against a planned "mega-basin" collecting water for irrigation in the western Deux-Sevres region, the 30-year-old has been struggling for his life in a coma.

His parents filed a complaint alleging attempted murder and blocking access for emergency personnel, which sparked the investigation.

The man from Toulouse in the southwest was gravely hurt, according to protest organizers, when a police tear gas grenade hit him in the head.

"People close to him are determined to bear witness and uncover the truth about what happened," they added.

Military prosecutors in the western city of Rennes, who have jurisdiction over France's gendarmes, or armed forces police personnel, are looking into the issue.

Warlike scenes of Saturday's clashes between around 5,000 protesters and 3,200 police in the open fields hit the headlines over the weekend.

Security personnel used helicopters, armored cars, water cannons, and thousands of tear gas grenades in a response that the DGGN police authority described as "proportionate to the level of threat."

Protest organizers reported 200 wounded and 40 critically injured, including one person who lost an eye.

Security forces have this week faced criticism for their heavy-handed tactics in dealing with the protests. On Friday, the Council of Europe warned that sporadic violence in protests "cannot justify excessive use of force."

On Saturday, local media reported that 15 investigations of police brutality against demonstrators have been opened in France amid the widespread protests.

According to BFM, investigations are centered on the use of excessive force and verbal threats by police teams against protesters.

It was further reported that three of the investigations were opened by the Paris public prosecutor, while the Interior Minister authorized the other 12 investigations.