French President Emmanuel Macron on Friday faced the gravest challenge to his authority since the so-called Yellow Vest protests after his government's decision to push through a contested pension overhaul without a vote prompted violent unrest overnight.
Cars were torched in Paris and other French cities during spontaneous demonstrations involving several thousand people. Trade unions urged workers to step up strikes on Friday and briefly blocked the Paris ring road.
Interior Minister Gerald Darmanin said some 310 people had been arrested by police and he promised to crack down on trouble-makers.
"Opposition is legitimate, protests are legitimate but causing mayhem is not," he told RTL radio.
The unrest was reminiscent of the Yellow Vest protests which erupted in late 2018 over high fuel prices and forced Macron into a partial U-turn on a carbon tax.
The pension overhaul raises France's retirement age by two years to 64, which the government says is essential to ensure the system does not go bust
In parliament, opposition lawmakers promised to file motions of no-confidence in parliament and called for Prime Minister Elisabeth Borne to resign.
However, there was little chance the fragmented opposition could unite to bring down the government. Conservative LR lawmakers having ruled out joining motions of no-confidence.
Votes in parliament were likely to take place over the weekend or Monday.
Labour Minister Olivier Dussopt told BFM TV that if those motions of no confidence were rejected, the pensions overhaul bill would "be enacted", downplaying the risk this could fuel further anger.
"I'm not in denial of the difficulties we are facing but, at a moment when things are moving, we must stay the course," he added.
Trade unions have called for a new nationwide day of strikes and demonstrations for Thursday March 23.