A deluge of millions of cubic metres of ice, mud and rock crashed down a mountain on Wednesday, engulfing the village of Blatten, and the few houses that remained later flooded.

Its 300 residents had been evacuated earlier in May after part of the mountain behind the Birch Glacier began to crumble.

Flooding increased yesterday as the mound of debris almost 2km across clogged the path of the River Lonza, causing a lake to form amid the wreckage, raising fears that the morass could dislodge and trigger more evacuations.

Late yesterday, local authorities urged residents in Gampel and Steg, villages several kilometres further along the Lonza Valley, to prepare for possible evacuation in case of emergency.

The army is standing by with water pumps, diggers and other heavy equipment to provide relief when conditions allow.

Rescue teams have been looking for a 64-year-old man missing since the landslide.

Local authorities suspended the search yesterday afternoon, saying the debris mounds were too unstable for now, and warning of further rockfalls.

Residents have struggled to absorb the scale of destruction caused by the deluge, an event that scientists suspect is a dramatic example of the impact of climate change in the Alps.