Masked activists clashed with police at a protest over a motorway project in southern France, leaving five people hurt, local officials said.

Thousands of demonstrators ignored a ban on gathering to protest at the site of the A69 motorway between Castres and Toulouse in the south-west.

A police officer, two paramilitary gendarmes and two protesters were injured during the clashes on Saturday, authorities said. 

The injured police officer was hit with a Molotov cocktail. Videos showed protesters launching the improvised incendiary devices at the police, who struggled as the flames spread around their feet.

Ecologists and Left-wing activists are trying to stop an extension of the motorway, which scientists say will destroy farmlands, wetlands, trees and underground water sources.

The first clashes broke out at around 3pm local time when “radicalised protesters... determined to commit acts of violence” tried to reach a main road, according to a statement from local officials.

Riot police used tear gas to try to disperse the demonstrators and keep them from the route to the construction site.

The prefecture, or local authority, of the Tarn region denounced “extremely violent attacks with catapults” and said the crowd contained “1,200 radical individuals”.

They had “clearly come to cause damage with no link to the issue” of the motorway, said a statement from Michel Vilbois, leader of the local authority.

“We have a duty to step in,” said one activist from climate campaign group Extinction Rebellion. “As long as we are there, the motorway will not go ahead,” she added.

Organisers of the protest, near the village of Puylaurens, said 7,000 activists had turned up. The prefecture put the figure at 1,600.

Some 1,600 police and gendarmes were deployed to deal with the protest, which was initiated by the Roue Libre group.

The new road, started early in 2023, has the backing of most local elected officials and is due to come into service at the end of 2025.