Hundreds of thousands of people were joining rallies in 230 French cities to protest government plans to raise the retirement age.
The nationwide protest kicked off in the southern city of Toulouse, where large crowds of protesters marched through the city center waving banners and chanting slogans critical of President Nicholas Sarkozy.
The unpopular pension reform includes a rise in the minimum retirement age from 60 to 62 by 2018. Under the bill, which has already passed the National Assembly and is scheduled to be voted on in the Senate on October 13, pensioners will receive a full pension at 67 instead of 65.
One of those demonstrating in Toulouse, a middle-aged worker, said many people are simply no longer fit to work after 65.
"I've contributed for 42 years. Isn't that enough?" the man said. "Can I even climb a ladder any more? At 65 years of age, you wouldn't be willing to climb a ladder either."
France's powerful unions were hoping to attract millions of protesters today for a fifth day of nationwide strikes and protests.
"Indications from our branch offices and comrades are that we should have a very, very large mobilization today," union official Jacques Bory told Reuters.
Workers at the country's 12 refineries and fuel depots went on strike on October 15, shutting down a fuel pipeline supplying Paris and its airports, and sparking reports of panic buying.
Many gasoline stations in the capital have already run out of fuel, despite riot police being dispatched on October 15 to ensure supplies continue to flow.
The strikes have severely disrupted air and rail traffic, and truck drivers are now threatening to block roads.
The CFDT union's trucking section said drivers may also block fuel depots, refineries, and food warehouses.
Another key worry for the government is the risk of protests becoming violent now that high-school students have joined the demonstrations.
The rallies have been relatively peaceful so far, although a policeman in Cannes was injured by a flying rock and doctors are struggling to save the eye of a 16-year-old teenager after he was struck by a rubber bullet.
Riot police used tear gas on October 15 to disperse protesters in Lyon, and dozens of students have been arrested across the country.