One of the largest high-school blockades and protests took place across France as students and unions demanded that the cash-strapped government fix understaffed and dilapidated schools.

The government said 256,000 people took part in Tuesday’s protests.

The nationwide protests marked the latest stage in a fortnight of demonstrations that began in Paris's deprived suburbs before spreading across the country, at times turning violent.

Most of the demonstrators were peaceful, but a minority clashed with police, lit fires and hurled projectiles.

“Right now, I think we need to stand in solidarity with young people,” said Michele Dalon, a 76-year-old protester in Lyon. “What kind of world are we leaving them?”

The government has responded by deploying riot police, leading to mass arrests and clashes resulting in injuries to protesters, police officers and school staff.

The Paris police said the protest march in the capital had attracted a large crowd and was proceeding smoothly.

But they said about 300 “hostile individuals” had gathered at the front of the demonstration.

“They are trying to make contact with the security forces,” the police said in a WhatsApp group shared with journalists.

Prime Minister Sébastien Lecornu said the government respected legitimate protesters but opposed outbreaks of violence.

“Extreme violence has knocked on the doors of these high schools ... And this extreme violence must be condemned unconditionally. In a functioning democracy, there can be no room for tolerance of violence,” he said.

Lecornu added that there was a right to protest and a legal framework to do so, and that he welcomed Tuesday's large street marches because they were taking place within that framework.

He denounced criticism that the government and police were racist and were intentionally acting to hurt protesters, calling these “lies that are dividing society”.

The unrest has piled more pressure on a government seeking to narrow a ballooning budget deficit six months before an election to replace President Emmanuel Macron.

French borrowing costs have surged in recent days to levels not seen since the early 2000s.