Those caught up in the avalanche were backcountry skiing in the mountains, said Emmanuel Coquand, spokesperson for the local authorities of Haute-Savoie.

He said authorities were still confirming the identity of the victims.

He said the avalanche was extensive, covering an area of 1km by 500m at an altitude of 3,500m and that its causes are being investigated.

The glacier lies near the village and ski resort of Les Contamines-Montjoie.

President Emmanuel Macron wrote on Twitter that rescue services were continuing to search for further casualties and that his thoughts were with the victims and their families.