French workers poured onto the streets Saturday to defend their right to retire at 60, as rolling strikes shut down oil refineries and threatened to leave Paris airports without fuel.

High school students bolstered nationwide protests against President Nicolas Sarkozy's plan to increase the minimum retirement age to 62, and Finance Minister Christine Lagarde told people not to panic as petrol pumps ran dry.

Interior Minister Brice Hortefeux has told police to "limit the use of force to what is strictly necessary" when dealing with any student unrest at Saturday's protests, the fifth in less than six weeks.

Unions want to pummel the government into backing down on pension reform plans, staging strikes on weekdays and mass demonstrations in cities at the weekend.

The interior ministry said that at least 340,000 demonstrators had taken to the streets by midday Saturday, fewer than what police said were 380,000 people at the last weekend protest on October 2.

The head of the FO union, Jean-Claude Mailly, said that turnout was the same as on October 2, more in some parts of the country, with hundreds of thousands taking part in Paris.

A nationwide day of strikes and demonstrations last Tuesday brought more than a million people on to the streets, and workers in some sectors have kept up their stoppages since then. Another mass strike is planned for next Tuesday.

"We're prepared to demonstrate under the snow if it takes that long," Airbus worker Stephane Thibault, 37, told AFP at a demonstration in the southern city of Toulouse.

"We're mobilised, everyone seems motivated. With right-wing governments, we know you have to resist," he said.

Strikes have shut down 10 out of France's 12 oil refineries, despite riot police being dispatched to keep the fuel flowing amid panic buying.

The government has given oil companies permission to tap into their own emergency stocks, but has resisted calls to open the part of the French strategic fuel reserve controlled by a government committee.

Lack of fuel forced the shutdown of a pipeline to Paris's two main airports.

The main Paris hub, Roissy Charles de Gaulle, has enough aviation fuel to last until Monday evening or Tuesday, the transport ministry said, with planes reportedly being told to arrive with enough fuel for the return journey.

"We have ways of finding a solution to supply the airport. We're confident," the spokesman told AFP, asking not to be named. "The pipeline supplying fuel to Orly and Roissy airports is working intermittently."

"There is no shortage," Finance Minister Lagarde told RTL television. "We have several weeks of fuel stocks," she said, with 230 service stations out of 3,000 dry of fuel.

Cars began queueing at petrol stations outside Paris from before dawn, an AFP correspondent reported, with diesel in particularly short supply.

"We don't have any left and we don't know when the next delivery will come," said a petrol station worker at a hypermarket at Clichy-sous-Bois who gave his name as Jean-Claude. "Petrol reserves are also extremely low."

Strikes against pension and port reforms at oil depots in the south of the country since September 27 have left 63 oil, gas and chemical tankers waiting off the Mediterranean coast on Saturday, Marseille port authorities said.

French truck drivers are also to join protests. "There's impatience, the guys are saying 'let's go'," said transport union chief Maxime Dumont

Railway operator SNCF said that on average two out of three high-speed TGV trains were running in and out of Paris, although only one TGV in four outside the capital. The Paris metro was running normally.

Because of a separate Belgian railway strike all high-speed Thalys trains between Paris and Brussels will be cancelled. Eurostar trains travelling under the Channel will be unaffected.

Unions and the Socialist opposition have vowed to defend the right to retire at 60. They accuse Sarkozy of making workers carry the burden for the failure of the financial sector, and have proposed increasing taxes on the rich.

The head of the powerful CGT union, Bernard Thibault, has warned that the protests might not end even after the government passes the reform law.

But the government has shown no sign of retreating from what is a cornerstone of Sarkozy's reform agenda as he prepares for his likely re-election battle in 2012.

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With AFP.