The Mont Blanc tunnel between France and Italy has reopened to heavy trucks, three years after a truck accident sparked a deadly fire inside the tunnel. Large groups of demonstrators protested the reopening of the mountain link between the two countries.

Local media report 2,000-3,000 protesters blocked the French entrance of the Mont Blanc tunnel early Tuesday near the picturesque valley of Charmonix. Protests also were reported on the Italian side of the tunnel.

Local citizens groups, environmentalists and unions organized demonstrations to voice outrage that big trucks are allowed once again to pass through the Alpine tunnel.

A collision involving a heavy truck in 1999 sparked a large fire in the tunnel that killed 39 people. The tunnel, which links France and Italy, was closed to all traffic for three years. During that period, engineers widened the artery and installed a number of safety measures to prevent a similar accident from occurring.

The Mont Blanc tunnel was reopened to autos and light vehicles earlier this year. But some citizens groups and environmentalists in both France and Italy said the ban should remain on big trucks. They argue the heavy trucks pollute the Alpine valley and are dangerous.

Heavy trucks were allowed to legally use the tunnel beginning at midnight. As of midday Tuesday, only a few had passed from Italy to France. And after French protesters blocked a Belgium truck from passing, no large trucks crossed the tunnel's entrance in France.

Truckers argue that tunnels like Mont Blanc are vital for hauling large amounts of merchandise between European countries. And French and Italian officials say the newly reopened Mont Blanc, along with tougher tunnel rules, mean chances are very unlikely for a repeat of the 1999 tunnel accident.