Hundreds of thousands of protesters gathered in cities across France on Saturday for marches that unions hope could crush President Nicolas Sarkozy's plan to raise the retirement age.
Union leaders want to bring enough people onto the street to make the government think again, while rail and refinery strikes continued to disrupt travel around the country.
Protesters were marching in Toulouse, in the south, and other cities by midday, waving red union flags.
The biggest crowds will be later in the day in Paris.
Five straight days of strikes over the unpopular reform have cut train services and grounded flights.
Walkouts at oil refineries have hit supply at two percent of France's petrol stations.
Economy Minister Christine Lagarde urged people not to panic over fuel as she said the
country had ample stocks for now.
"We have reserves," she told France's RTL radio, adding supply problems had affected 230 petrol stations out of a total 13,000 in the country. "People mustn't panic," she said.
Sarkozy is determined to overcome the powerful trade unions and push ahead with his pension reform, saying it is the only way to stop a 32-billion-euro annual pension shortfall ballooning to 50 billion by 2020.
Lagarde told RTL that gradually lifting the minimum and full retirement ages by two years would be less painful than raising pension contributions or trimming retirement benefits for the 15 million people in France currenty receiving them.
The government and unions will be looking closely at Saturday's turnout. Unions said nationwide demonstrations on Tuesday drew 3.5 million protesters. The Interior Ministry put the figure at 1.23 million.
The government's main concern is youth protesters becoming rowdy. Riot police used tear gas on Friday to disperse crowds in the city of Lyon.
Dozens of students were arrested across the country and several police officers were injured.
Rail services were reduced on Saturday, but flights out of Paris's Orly airport were back to normal following disruption on Friday from a strike by runway workers.
In another sign of growing momentum to stop the minimum retirement age rising to 62 from 60, truck drivers -- the heavyweights of French demonstrations because of their ability to block roads -- could join Saturday's action.
France has a long tradition of overpowering unpopular government proposals through street militancy, although polls suggest French people are coming to terms with the fact that delaying retirement, in line with other European countries, is becoming inevitable.
Strikes during the week at French oil ports and refineries put pressure on fuel supplies and cut the flow at a pipeline running into Paris and international airports.