French President Nicolas Sarkozy vowed action against strike-induced fuel shortages threatening the economy today as workers and students rallied en masse to defend their right to retire at 60.

The interior ministry said 480,000 protestors had poured onto the streets by midday, slightly down on the 500,000 at the last weekday protest, as youths battled police, petrol stations ran dry and flights were cancelled.

Union estimates for turnout, frequently three times higher than those of police, were not immediately available.

With over 200 protests planned for Tuesday's day of action, the sixth since September, and all 12 French oil refineries shut down by strikes, Sarkozy said the cabinet would draw up a plan to stop France grinding to a standstill.

"In a democracy, everyone can express themselves but you have to do so without violence or excesses," Sarkozy told journalists in the French resort of Deauville following a summit with Russian and German leaders.

"I will hold a meeting as soon as I return to Paris to unblock a certain number of situations, because there are people who want to work and who must not be deprived of petrol."

Production at French oil refineries has been shut down since last week and fuel shortages have hit more than 2,600 petrol stations, or around one in five nationwide, according to an AFP tally of oil industry figures.

French fuel and heating federation FF3C said the "extremely worrying" situation "should definitely be called a shortage," while the International Energy Agency said France has "sufficient stocks" to deal with the situation.

Authorities in Normandy requisitioned 12 petrol stations for use by rescue and emergency services, while Prime Minister Francois Fillon said a third of departments or local administrations were experiencing fuel shortages.

Fillon said that the government's fuel resupply programme would see the situation restored to normal in four or five days' time.

The head of the national road haulage association, Jean-Paul Deneuville, told AFP that "the end of the week is going to be very difficult" with many transport companies unable to work because of the fuel shortages.

While the Paris metro is running almost normally, people in rural areas are finding it increasingly difficult to get to work, the CPME association of small and medium businesses said.

The interior minister promised tough action as clashes erupted anew outside a secondary school in Nanterre, near Paris, where youths burned a car and threw rocks at riot police for the second day in a row.

Police fired tear gas and arrested nine youth protestors in the central city of Lyon who had overturned cars and set one alight.

The ministry said that 1,158 troublemakers had been arrested at demonstrations since the start of the week, 163 of them on Tuesday morning.

Truckers staged go-slows on motorways near Paris and several provincial cities, while drivers blocked access to goods supply depots and joined oil workers blocking fuel depots to defend their right to retire at 60.

The powerful CGT union's transport section called for their strike action to be renewed on Wednesday, encompassing airport staff, air traffic controllers, public transport workers and employees of national railways operator SNCF.

Former Socialist prime minister Laurent Fabius appealed to Sarkozy to open dialogue with the unions, warning of possible "excesses."

Half of flights from Paris Orly airport were to be cancelled on Tuesday, and around one in three at the main Roissy-Charles de Gaulle and regional airports.

Slightly over half of express TGV trains were to run, while the Eurostar line under the Channel to London was expected to operate normally and nine out of 10 high-speed Thalys connections were to run to Belgium.

As well as train workers and truck drivers, postal workers, telephone employees, teachers and sections of the media are also on strike.

Unions want to force Sarkozy to abandon a bill to raise the minimum retirement age to 62, which is in the final days of its journey through a parliament in which the right-wing leader enjoys a comfortable majority.

Most French back the current protests, with a poll published Monday in the popular Le Parisien daily showing that 71 percent of those asked expressed either support or sympathy for the movement.