The 56-year-old man, who was roped to his son and two daughters, plunged 1,600ft down a slope of rock, ice and snow as their mother watched from below, said Oscar Tajola, head of the mountain rescue corps in the nearby town of Courmayeur.

"We had to take her to hospital because she was in shock," Mr Tajola said by telephone. "We think one of them slipped and pulled the others down."

The 50-year-old woman was later released from hospital and identified the bodies of her husband and her children, aged 17 to 23, police in the ski-resort town said.

The family, from the Netherlands, were climbing 12,500ft Mont Dolent, which is part of the Mont Blanc massif.

The 15,780ft Mont Blanc straddles Italy and France and attracts hundreds of climbers a year. Dozens of them die on the massif each year.