High winds and rising temperatures caused the avalanche which engulfed John York, 38, on Thursday morning.

Emergency services said he suffered massive internal injuries when he was buried by frozen debris as the slab of ice broke off the glacier on Mont Maudit in the French Alps.

He was descending the mountain with his brother and three others.

'Unlucky to be in the way'

The French mountain rescue spokesman said: "A block of ice about the size of a car sheered off the mountain and broke into smaller pieces in the path of the climbers.

"The dead man was killed almost instantaneously. He had been swept along with the others over a very great distance. It was a pure accident.

"It is in the nature of these mountains that sudden falls of ice and snow happen. This man and his colleagues were unlucky to have been in the way when it happened."

The group, which included French and German climbers, had set off from its base in Switzerland and followed one of the most popular routes on the mountain which links Mont Blanc to its two sister peaks.

A spokesman from the Foreign Office said the tragedy was being investigated by French authorities.