PARIS — Diesel and jet fuel supplies were running low Saturday in parts of France as workers took to the streets for another nationwide protest against President Nicolas Sarkozy's plan to raise the retirement age to 62.

Fuel supplies were a prime concern as unions announced that all 12 fuel-producing refineries in France were on strike and many depots were being blocked by protesters. Police were called in Friday to force three crucial fuel depots to reopen, including one near the southern city of Marseille.

Saturday's march from the Place de la Republique in Paris was the fifth in a month of protests that have swept this nation of 64 million people, affecting trains, subways, airports, hospitals, and schools.

The Ecology Ministry said fuel stocks at Paris' Charles de Gaulle airport — one of Europe's key hubs — were good until at least Tuesday.

Dominique Bussereau, France's transport minister, authorized oil companies to use some reserves after trucking companies complained of difficulties finding fuel, but he insisted there was no reason to fear a gas shortage.

Still, a sign Saturday at a gas station in Feyzin, near the eastern city of Lyon, announced a fuel shortage at all pumps.

"When the government says there will be no shortage, it means there will be a shortage," said Bernard Martin, a 60-year-old retiree who found no fuel at a Carrefour gas station in Ecully, near Lyon.