Image copyright AFP Image caption The Pakistani top brass says posting troops on Siachen has been a military necessity

The devastating avalanche which has buried 140 people - 129 of them Pakistani soldiers - on the Siachen glacier has once again highlighted the dangers faced on the world's highest battlefield. BBC Urdu's Zaheeruddin Babar visited the area in disputed Kashmir to see the huge challenges facing rescuers searching for those entombed in the snow.

At 13,000ft (3,962m) above sea level, the Giari Sector of the Siachen glacier is not for the faint-hearted. The high altitude brings freezing conditions - temperatures here can drop to -50C (-58F). The weather rather than the Indian army has accounted for the deaths of 90% of the 3,000 Pakistani soldiers who have perished here since 1984.

Once you have acclimatised to the thin air and the cold, the most striking thing about the Giari Sector are the frantic efforts to rescue those buried in the huge avalanche of 7 April.

On that fateful day many thousands of tonnes of snow, boulders, slush and ice engulfed the biggest and the main Pakistani military camp near the glacier. In places the snow covering the camp is believed to be up to 60m deep (200ft), covering a 1 sq km area - equivalent to several football pitches.

Avalanche alert

It is no exaggeration to say that it is like looking for a needle in a haystack - yet the size of the challenge does not seem to deter troops dressed in white jackets, heavy boots and white woollen caps driving bulldozers back and forth, churning up the packed snow and ice.

Media playback is unsupported on your device Media caption The BBC's Orla Guerin reports from the rescue site

The army faces a huge logistical challenge apart from the unyielding weather - which only allows for intermittent travel to the area - and the sheer scale of the disaster.

On top of that are the difficulties of transporting - and then maintaining - heavy snow-removing equipment.

In the middle of this forlorn landscape stands a small sign that says "ops room". It may have been positioned directly above the area where rescuers estimate the former operations room of the camp is located, buried beneath the snow.

Rescuers are at risk of further avalanches in this area, surrounded by some of the most imposing mountains in the world.

Amid the din of the heavy snow-removing machinery which works around the clock, an army officer tells visitors that if they hear a prolonged blast of his whistle - signifying an avalanche alert - they are immediately to abandon whatever they are doing and run quickly for cover.

Most of the time, however, troops are focused on finding their colleagues - or at least recovering their bodies.

Officers say that in the backs of the soldiers' minds is the fact that those buried under the snow are colleagues with whom they lived and worked very closely in immensely tough conditions.

The rescuers want to ensure that their brothers-in-arms are either recovered or brought home for burial.

That is why the rescue effort itself shows no sign of abating, nearly two weeks after the avalanche.

There is little chance of finding survivors but it might still be possible that some survivors could have taken shelter and found themselves in an air pocket after the avalanche buried them. The camp was well equipped with food and other supplies, troops say.

Inhospitable of places

"We are working in shifts... there are 139 people below the [site of] the avalanche and 400 above it. Our sole aim is to rescue those buried under the avalanche, and we will," Maj-Gen Ikram-ul-Haq told me.

While the army insists that the morale of troops has not been unduly affected by the disaster, questions nevertheless continue to be asked as to why exactly soldiers need to be based in this most inhospitable of places.

On Wednesday army chief Ashfaq Pervez Kiyani voiced those doubts, pointing out that environmental damage caused by the military's presence - coupled with the huge expense in human and financial terms of basing troops there - all added weight to calls for both India and Pakistan to withdraw from the glacier.

However the general was careful to state that the only reason Pakistani troops are here is because of the threat posed by Indian troops posted nearby.

The high altitude which makes breathing so difficult means that everything here is calculated, from walking to speaking.

Yet the utter absurdity of posting troops here has not dampened the spirits of the rescuers or their concern for visitors. Time and again I was warned by soldiers of the health risks of being in the area.

I quickly realised that the three colonels and four soldiers assigned to me were not so much curtailing my freedom to report but keeping an eye on my physical wellbeing.

After 50 minutes in the area my knees ached, my lips were dry, my nose was running and I was acutely short of breath.

The toughness of the posting also had an obvious effect on the soldiers - some could not process words quickly and some appeared lethargic in their responses to my questions - they spoke slowly and frequently had to take deep breaths.

It is hardly surprising that more soldiers here have died from the harsh weather than in combat - this is a place where humans are not meant to be.