'Surviving for 17 hours in an avalanche and being found conscious and in a state of mild hypothermia is an extraordinary event," the police said.

The young Swiss had been skiing off-piste in the Evolene region of southern Switzerland when he was caught in an avalanche that left him trapped under 50cms of snow.

His family reported him missing yesterday afternoon and a search and rescue team found him at dawn after spotting movements in the snow from their helicopter.

The skier apparently managed to survive so long by forming an air hole above his face in the snow.

Avalanches in the Alps have killed eight people in France and 11 in Austria since the start of this month.