Rescuers searching for 138 people buried by an avalanche at a high-altitude Pakistani army camp are to dig a deep tunnel into the huge mass of snow and ice, the military said Thursday.

A huge wall of snow crashed into the remote Siachen Glacier base high in the mountains in disputed Kashmir early on Saturday morning, smothering an area of one square kilometre (a third of a square mile).

Search teams are looking for the trapped soldiers and civilians at six different points on the site, around 4,000 metres (13,000 feet) up in the mountains.

At one, mechanical excavators dug down through 35 metres (115 feet) of snow, the military said, and rescuers were about to start work on a 40-metre horizontal tunnel to reach the camp's accommodation area. Excavation work has gone down 30 metres at another site.

More than 450 rescuers are working in sub-zero temperatures at the site, though experts have said there is virtually no chance of finding any survivors.

Military photographs showed diggers and rescuers at work on an almost featureless expanse of dirty grey snow and ice, with no trace visible of the camp that had been the 6th Northern Light Infantry headquarters.

The site lies near the de facto border with India in the militarised region of Kashmir, which has caused two wars between the neighbours since independence in 1947.

The nuclear-armed rivals fought over Siachen in 1987, but guns on the glacier have largely fallen silent since a peace process began in 2004.