President Nicolas Sarkozy dispatched riot police yesterday to reopen fuel depots blocked by strikes against pension reform, as the fuel pipeline to Paris airports was cut and all France’s refineries shut down.

But even as officers forced open the barricades at some depots, strikers threw up new pickets at other fuel distribution centres across the country to fight against moves to raise the retirement age from 60 to 62.

Riot police made 16 arrests and used tear gas as they fought running battles with youths who pelted them with stones and overturned cars during street protests by high-school students in the central city of Lyon.

Students protested outside the prime minister’s offices in Paris and took to the streets in demonstrations across France, where hundreds of schools were hit by a fourth consecutive day of blockades or other actions, officials said.

The interior ministry said that more than 150 vandals and troublemakers had been arrested at student protests nationwide.

Mr Sarkozy took the decision to send in the police to prevent fuel shortages amid reports of panic buying after workers at all of France’s 12 refineries walked out to join the broader protest.

“The goal of this reform is to guarantee to all French people that their retirement and that of their children can be paid for,” Mr Sarkozy insisted.

“As head of state my duty is to look to the future and not profit from the past,” he said, accusing his opponents of ignoring the reality of the growing shortfall in the social security fund, which fuels France’s budget deficit.

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

“Pensions must be reformed, everyone agrees. To do that we need to discuss things, to negotiate, and we need fairness,” Socialist leader Martine Aubry said, accusing Mr Sarkozy of provoking an unnecessary confrontation.

Meanwhile, fuel distributors said several hundred filling stations had to shut yesterday because supplies had run out.

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.

Workers at a depot in Fos-sur-Mer on the Mediterranean did not resist when police intervened to reopen the facility, unions said.

Officials in the south of the country said that as a result “there will be no shortage of refined fuel products in the medium-term... and no rationing.”

All 12 French refineries were closed yesterday, although two reopened later in the day, forcing the shutdown of the fuel pipeline to Paris’s two main airports as well as depots outside the capital, the pipeline operator Trapil said. The main Paris air hub, Charles de Gaulle-Roissy, could run out of fuel as early as next week, a company spokesman said, adding that three fuel depots supplying road filling stations south of the capital would also be hit.

“Orly airport has stocks for 17 days, and Roissy for at least the weekend,” he said, explaining that the pipeline carried petrol, diesel and aviation fuel from the Grandpuits refinery east of Paris.

“We are fine for a few days,” a spokesman for Paris airports authority said, asking not to be named. “The situation is normal, there’s no need to panic ... the situation is evolving.”

France’s main unions have upped the ante in their fight against pension reform, calling for their members and supporters to hold the fifth in a series of street rallies on Saturday and another one next Tuesday.

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.

Despite the ongoing strikes and protests, the current government shows no sign of retreating from what is a cornerstone of Mr Sarkozy’s reform agenda as he prepares for his likely re-election battle in 2012.

Key sections of the reform have been passed by the upper house Senate and the government hopes for it to be passed in its entirety by late October.