French President Emmanuel Macron said on Wednesday that France's student protesters are being "exploited" by political forces months ahead of the country's presidential elections. Hard-left candidate Jean-Luc Melenchon participated in a Paris demonstration while hard-right frontrunner Marine Le Pen voiced support for police deployed to protests.

French President Emmanuel Macron believes students waging three weeks of protests that have closed many schools have "legitimate" grievances but are also being "exploited" by political forces, a government spokeswoman said Wednesday.

The leader, who is in his final six months of office, has asked the government to come up with "concrete responses" within weeks to the unrest by high school pupils, spokeswoman Maud Bregeon told reporters.

She spoke after Macron held his weekly meeting with his cabinet, a day after nationwide solidarity demonstrations showed significant support for the students.

The interior ministry said 161,500 people turned out for Tuesday's demonstrations held in Paris and other cities. Unions organising the rallies put the figure at 480,000.

Some violent scenes erupted on the sidelines of marches in Paris and Lyon, with police firing tear gas in response.

In his cabinet meeting, Macron "stressed that young people have legitimate concerns, but said these are being exploited for political purposes and turned into urban violence", Bregeon said.

With French presidential elections due in April and May next year, some opposition parties have seized upon the demonstrations.

Jean-Luc Melenchon, the presidential candidate for the far-left France Unbowed (LFI) party, participated in one of the Paris demonstrations.

The far-right National Rally (RN) party of Marine Le Pen, whom surveys give as the frontrunner for the elections, has voiced support for police deployed to the protests and blamed students for violent episodes.

Alleged police brutality Students, unions, rights groups and parents have accused the police of brutality against the students, with some of the young protesters maimed.

The family of one 15-year-old high school student who lost his hand when a police stun grenade exploded said Wednesday they had started legal action to demand an "impartial" investigation.

One of the family's lawyers, Bertrand Wattez, said the boy, Evan, denied the police account, relayed by prosecutors, that he had tried to pick up the grenade when it went off on October 5. He also denied participating in the student protests in his city of Lens. The lawyer said that Evan not only lost his left hand as a result of the blast but also several fingers on his right hand.

In another violent incident, a 16-year-old student was blinded during a September 30 protest outside his school in Tours. His family blamed the police. Late Tuesday, the prosecutor for Tours said the officer involved had been charged with aggravated battery.

Police have opened internal investigations into 36 allegations of officer violence against demonstrators, according to the interior ministry. Interior Minister Laurent Nunez said nearly 900 police officers had also suffered injuries during the protests.