A number of Alpine communities in Switzerland's Lötschental valley have been asked to be ready to evacuate their homes following a massive landslide on Wednesday.

Rivers in the area have become swollen and have dammed up behind the rubble, rock and ice that thundered down into the valley after the Birch Glacier began to collapse in the southwestern canton of Valais.

"We ask residents to make personal preparations so that they can leave their homes as quickly as possible," the municipalities of Steg-Hohtenn and Gampel-Bratsch in the Lötschental valley posted on their website late Thursday.

Man still missing after Wednesday's collapse

Wednesday's collapse saw millions of cubic meters of ice, mud and rock engulf the village of Blatten and authorities have yet to locate a 64-year-old man who has not been seen since the collapse.

Blatten's 300 residents were evacuated at short notice last week following an assessment by geologists that found that a landslide was imminent.

Local authorities suspended the search for the missing man on Thursday afternoon, as conditions became too dangerous with warnings of further rockfalls.

Rising water levels a concern

The debris has blocked the course of the River Lonza and has caused a lake to form, which in turn has heightened fears the mass could dislodge and impact communities further downstream.

Stephane Ganzer, head of the security division for the Valais canton, told reporters that water levels have been rising by 80 centimeters (31.5 inches) an hour as a result of the blockage.

The army is on standby with water pumps and earth-moving machinery and will get to work once conditions improve.

Edited by: Wesley Dockery