Explosion at Mont Blanc Tunnel

A small explosion occurred at the French entrance to the Mont Blanc tunnel early today, several hours before the long-awaited reopening of the Alpine passage, destroying a maintenance truck but causing no injuries.

The blast caused no damage to the tunnel itself, which has been closed since a 1999 truck fire killed 39 people.

The passage linking France and Italy was expected to reopen to cars at noon as originally scheduled.

No one immediately claimed responsibility for the blast, which occurred at about 3am.

The explosive device was described as low-grade, of the type used often in the Alpine area to trigger avalanches.

Police began taking positions at the tunnel's entrance by dawn, as part of security measures planned for the reopening later in the day.

Two other attacks against the tunnel last year, while it was still closed to traffic, were claimed by activist groups that opposed truck traffic in the Alpine passage.

Demonstrations were planned today in protest at the tunnel's eventual reopening to trucks, which government officials say will happen next week.

Environmentalists and other critics say that trucks inside the 7.4-mile tunnel are too dangerous and cause excessive pollution.

In March 1999, 39 people were killed after a truck carrying flour and margarine caught fire and turned the passage into a deathtrap.

The blaze burned for two days while firefighters tried to reach cars and people trapped inside.