India, Aug. 31 -- Drone footage has captured the dramatic moment when a huge mass of glacier ice and rock broke away from a mountain slope in Nepal, shortly before catastrophic flash floods swept through parts of the country and neighbouring Tibet.

The footage, recorded accidentally by a Chinese photographer, shows a vast section of bedrock and glacial ice collapsing near Langtang Lirung, a peak rising more than 7,200 metres above sea level.

As the mass broke away, enormous clouds of dust rose from the mountainside.

The mixture of ice, rock, mud and debris then plunged towards the valley below, about 1,200 metres beneath the collapse site.

The resulting surge contributed to a dramatic swelling of the Bhotekoshi and Trishuli rivers, tr...