Helicopters were used to rescue 48 people and about 30 in cars closest to the ground were able to climb down. But as night fell in the French Alps, the aerial operation had to be suspended, leaving more than 30 people dangling above the slopes.

Georges-Francois Leclerc, an official of the Haute-Savoie region, said conditions became very difficult as cloud cover increased. Twelve people were later evacuated by Italian rescuers, he said.

“We were forced to stop rescue operations at 8:45pm” for safety reasons, the dark and the weather making it too dangerous, he said, adding that they were not able to “guarantee the safety of the pilots, rescuers and the people stuck in the cars”.

Earlier a delicate operation involving three helicopters from Switzerland, France and Italy managed to bring dozens to safety in about an hour and a half.

A tourist told local radio station France Bleu Pays de Savoie: “The last hour was very, very long. We called the [Mont-Blanc] company, who explained to us that three cables had become tangled and there was only one left to un-cross but they weren’t able to do it.

“They tried to evacuate us but it was very difficult. I had to close my eyes for a good while and try to think about something else.”

During the night a team of five rescuers – three French and two Italian police officers – also attempted to reach the trapped tourists. One of the officers managed to get into a car that contained a 10-year-old child.

Those still stuck had access to emergency blankets, energy bars and bottles of water in the cars, authorities said.

At about 8am on Friday morning the cable cars were repaired and the remaining people were brought down.

The Vallee Blanche cable cars – each of which carries four people – connect Aiguille du Midi on the French side of the mountain with Pointe Helbronner on the Italian border, where the rescued passengers were taken.

The three-mile (5km) journey usually takes about 30 minutes to complete.

The problem was caused by cables that got crossed for “unknown reasons”. Employees of the Mont-Blanc company were unable to repair them, said its chief executive, Mathieu Dechavanne.

“We are in contact with the clients [in the cable cars]. They have water and some means of communication but are beginning to find it’s taking a long time,” he said.

The mayor of Chamonix, Eric Fournier, said there was “nothing fundamentally to fear”.

The Vallee Blanche cable car runs during the summer season, when large numbers of climbers and tourists flock to the area. Another series of cable cars takes skiers and visitors to the top of the Aiguille de Midi year-round.

The incident comes five years after around 40 people were stuck for nearly seven hours on the Grande-Motte cable car in the south-eastern French Alps after it broke down. They were evacuated through trap doors in the floor of the cars, using ropes to reach the ground 40m (130ft) below.

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