France and Spain opened a new cross-border tunnel as mayors and environmental groups led protests warning of the dangers of truck traffic through the passage.

The French and Spanish governments say the 5.3-mile Somport tunnel through the western Pyrenees mountains will ease traffic on the top of the range and foster economic growth.

Buses, cars and trucks began using the single-tube passage Friday night. Among the largest towns near the tunnel are Oloron, France and Huelca, Spain.

The opening was delayed by three years while crews put in extra security measures that governments required after a 1999 truck fire in the Mont Blanc tunnel between France and Italy. That fire left 39 people dead.

Construction of the Somport tunnel began in 1994 and was partly funded by the European Union.

Local leaders who are concerned about the threat of deadly tunnel accidents say the tunnel is too narrow for large trucks.

Noel Mamere, a leader of France's Green Party, said air pollution caused by the vehicle traffic would "ruin" the pristine Aspe Valley in France, which is home to the last bears of the Pyrenees.

Small groups of protesters lined roads throughout the region in France, and at least thirteen mayors from the Aspe Valley boycotted the opening in protest.

Officials estimate that an average of 1,400 vehicles, including about 250 heavy trucks, will pass through the tunnel each day this year _ though opponents say they believe the figures will be much higher.

The opening came a day after the European Union head office proposed tough new safety standards for road tunnels in the wake of several deadly accidents.

The plan encourages the construction of twin-tube tunnels to provide another escape route in case of fires or pileups.

EU Transport Commissioner Loyola de Palacio joined French Transportation Minister Gilles de Robien and Spanish Development Minister Francisco Alvarez Cascos for the inauguration of the tunnel.