Cars were torched in Paris and other French cities Thursday evening during otherwise peaceful demonstrations against raising the pension age involving several thousand people. Trade unions urged workers to step up and briefly blocked the Paris ring road on Friday.
A broad alliance of France's main unions said they would continue their mobilisation to try and force a u-turn on the changes. Protests took place in cities including Toulon on Friday, and more were planned for the weekend.
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.
"Something fundamental happened, and that is that, immediately, spontaneous mobilizations took place throughout the country," hard-left leader Jean-Luc Melenchon said. "It goes without saying that I encourage them, I think that's where it's happening."
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.
The French are deeply attached to keeping the official retirement age at 62, which is among the lowest in OECD countries. It is also considerably lower than the full retirement age in the United States.
More than eight out of 10 people are unhappy with the government's decision to skip a vote in parliament, and 65% want strikes and protests to continue, a Toluna Harris Interactive poll for RTL radio showed.
In reaction to the retirement age change done without a parliament vote, opposition lawmakers said they would file motions of no-confidence in parliament later on Friday.
Votes in parliament were likely to take place over the weekend or Monday.
