Paris, France (CNN) -- French workers -- upset that the government might make them wait until age 62 to retire -- extended their strike into a third day Thursday, and while transportation appeared to be improving, the situation at oil refineries was not.
The Paris Metro was running smoothly and there were no strikes at airports Thursday, but some railway workers on regional, national and high-speed trains were still off the job.
Work ceased at seven of France's 12 refineries as workers there continued the strike, the French Union of Petroleum Industries said.
There were fears that the work stoppage would disrupt French fuel supplies, but Total -- which owns six of the seven affected refineries -- said the situation was still normal Thursday. More than 98 percent of its gas stations were operating without difficulties, Total said.
Tankers had problems being loaded in the city of Nantes, Total said, affecting the operation of two gas stations there.
Also Thursday, 342 high schools across the country -- or nearly 8 percent -- were "disrupted" because students joined the protests and blockaded some schools, the Education Ministry said.
The Union Nationale Lyceenne, the French high school student union, said 500 high schools were "mobilized" Thursday.
The open-ended strike is over government pension reforms, which have passed the lower house of Parliament and are now awaiting approval by the Senate.
Workers are especially upset over plans to raise the retirement age from 60 to 62, which has already passed both houses of Parliament. It will not become law, however, until the Senate approves the full spate of reforms.
French President Nicolas Sarkozy, speaking in Bordeaux Thursday, indicated the government was not going to back down. "Our duty is to act, to act in the public interest, act with justice, but to act," he said, according to a report in the Paris daily newspaper Le Monde.
Wednesday, more than 1 million people walked out to protest the reforms.
Ten out of 12 French oil refineries were hit by the strikes Wednesday, with eight of them fully or partially stopped, according to the French Union of Petroleum Industries.
The Ministry of the Interior said as many as 1.2 million people walked off the job Tuesday, while unions put the figure at 3.5 million. There were also about 250 demonstrations across the country Tuesday.
Unions have said this strike -- the fourth in the past month -- is open-ended, and that workers will vote each day whether to continue the strike the following day. Previous strikes have lasted for 24 hours each time.
CNN's Saskya Vandoorne contributed to this report.