ISLAMABAD (AFP) - Up to 135 people, mostly soldiers, were feared dead Sunday after an avalanche buried a Pakistan army camp in mountainous Kashmir, in an area known as the world's highest battleground.

The avalanche early Saturday engulfed the camp near the Siachen glacier, an inhospitable area that nevertheless became the site of fierce fighting between nuclear-armed rivals Pakistan and India.

No survivors had been found after a huge all-day search involving more than 150 soldiers, sniffer dogs, and helicopters through the avalanche that covered an area of one-square kilometre (a third of a square mile).

The search was called off late Saturday as darkness set in and the weather worsened, but was due to resume at first light Sunday.

In a statement late Saturday, the military said that up to 135 people "including 124 army soldiers and 11 civilians... came under a huge snow slide early this morning" in mountainous Gayari district.

Among the missing were a colonel, a major, a captain and four junior officers, said the military, in a list of those missing under the snow.

A tailor and two hairdressers were among civilians buried as the avalanche hit the militarised region, which is close to the de facto border with India in the Muslim-majority Kashmir region, over which India and Pakistan have fought two wars.

Siachen became a flashpoint when India occupied key areas in 1984, including the heights, prompting Pakistan to immediately respond by deploying its own forces.

India and Pakistan fought a fierce battle over Siachen in 1987, raising fears of all-out conflict, although the guns on the glacier have largely fallen silent since a peace process was launched in 2004.

After 12 hours of searching on Saturday, army spokesman Major General Athar Abbas told AFP that, contrary to local media reports, no bodies or survivors had been found.

Pakistan's Prime Minister Yousuf Raza Gilani expressed his deep shock at the avalanche, but insisted in a statement that the disaster "in no way would undermine the high morale of soldiers and officers."

Heavy machinery to assist with rescue efforts has been transported to the far-flung and deeply inhospitable area, a security official said. A team of doctors and paramedics were also rushed to the region after the avalanche.

The avalanche struck early in the morning, a military statement said, raising the possibility that the buried soldiers were asleep at the time.

India and Pakistan have spent heavily to keep a military presence there.

India reportedly forks out more than 40 million rupees ($800,000) daily on its Siachen deployment -- a figure that does not include additional wages and bonuses.

Experts have previously said that India has around 5,000 troops on the glacier, while Pakistan has less than half that number. The harsh weather and altitude claim many more lives than actual fighting.

Avalanches and landslides frequently block roads and leave communities isolated in the mountains of Pakistan, neighbouring Afghanistan and in Kashmir.

In February, at least 16 Indian soldiers on duty in the mountains of Kashmir were killed when two avalanches swept through army camps.

Kashmir has caused two of the three wars between India and Pakistan since their independence in 1947 from Britain.

Underlining the uneasy relationship, President Asif Ali Zardari will on Sunday become the first Pakistani head of state since 2005 to visit the arch-rival.

During what officials from both sides describe as a "private" one-day visit, Zardari will be the guest of Indian Prime Minister Manmohan Singh in New Delhi before heading to an important Muslim shrine to offer prayers.