The teenager was hit in the chest as climbed at 1,600 metres (5,250 feet) towards the Werfen ice caves, police said.

"Four hundred metres above the site, a rock of about two cubic metres in volume broke away after heavy rains on Saturday," said geologist Gerald Valentin.

The Werfen ice caves, which stretch 42 kilometres (26 miles), were discovered in 1879 and are considered to be the largest network of ice caves in the world, attracting up to 2,500 visitors a day in high season.