The BBC's Claire Doole: "How the cable hurtled to the ground remains a mystery"

The accident happened just before 0730 (0530 GMT), as the cable car was climbing to the summit of the 2,700m Pic de Bure above the town.

There are conflicting reports as how the cable car fell. The local authorities initially said that the cable itself had snapped. But later, it was suggested that somehow the cabin had become detached from the cables.

Delphine Keilty of the Prefecteur's office: The rescue team is on site

An official from the cable car union said that the car had been built in 1981 and had just passed a safety inspection.

However, the relevent ministry says that as a privately owned installation, the cable car would not have been its responsibility.

In any case, the car fell 80m on to rocks shortly before arriving at the summit, and was smashed into fragments.

The BBC's Stephen Jessel: No-one knows how the car became detached from the cable

Rescuers, who soon reached the scene, found no survivors.

Twenty bodies were recovered from the wreckage and taken to the local church.

The cable car was privately owned by a Franco-German scientific enterprise and used to transport staff and equipment to an observatory high in the mountains.

It was not used by tourists or the public at large.

Passengers included building workers, cleaning staff, scientists and telecommunications engineers.

Mayor Jean-Michel Bernard said: "They were all locals. They all lived here."

The small village has only 545 residents.

The number of dead is the highest toll since 1976 when 42 people died at Cavalese in the Italian Dolomites, the world's worst cable car accident.