A father comforts his son injured by the earthquake at a makeshift hospital set up in a lawn of Ayub Medical Hospital in Abbotabad

South Asian governments and international relief agencies have begun a gigantic relief operation where last week's 7.6 magnitude earthquake killed more than 20,000 people. The immediate priorities are preventing further death, among the two to three-million survivors of the disaster.

Across the disaster zone in the Himalayan Mountains and nearby areas, the focus of efforts is turning to providing food, shelter and medical care to the survivors of the killer earthquake.

Ben Phillips, a South Asia policy coordinator from the international relief agency Oxfam, says their top concern is to ensure that millions of homeless people get adequate shelter before the onset of winter. He says old people and children will be particularly vulnerable as temperatures begin to dip dangerously low on the mountain slopes.

Quake victims in india

"People are sleeping under plastic sheeting and blankets which is OK for now, but it will soon be winter in Kashmir," he said. "Snow will start falling in one or two weeks ... and then people will need winterized tents. The numbers who have died could go up, because in the first wave people were killed by the earthquake, in the second wave ... they are killed by the fact that they do not have the resources to survive ... shelter, food, heat."

There is one silver lining to the cold weather. Aid workers say epidemics of water-borne diseases do not pose a major threat in the chilly mountain climate, although malaria and measles still present a danger.

Relief agencies are also concerned about approximately 50,000 people who were badly injured in the quake. In many of the affected areas, health facilities lie in ruins. What is left is overstretched, hospitals are overflowing with patients, and there are fears that hundreds of injured people may not even have been reached.

The head of The Federation of Red Cross and Red Crescent Societies in South Asia, Bob McKerrow, says medical relief, including field hospitals, is needed on a large scale.

"I am very worried ... particularly patients in hospitals are lying outside of hospitals ... and yesterday it hailed and it snowed and these are people who are injured," said Mr. McKerrow. "We have got to get big hospital tents in to ensure that those who are wounded have some sort of shelter."

Supplies are arriving every day, and the relief is slowly beginning to make its way to the affected areas. But the more isolated areas are still waiting for help. Trucks and helicopters to ferry the aid are just now being made available, the journey up narrow, winding mountain roads is taking hours, and torrential rain and hail is slowing the effort down.

Mr. McKerrow of the Red Cross says it may be days before some communities see the relief trucks.

"Within, say, two to three days, we should get adequate food, shelter, blankets to the accessible areas," added Mr. McKerrow. "As more helicopters become available we have to make sure we really get out to those remote areas, that may take four or five more days to do that. It is massive."

International aid agencies say they are preparing for a long-haul operation that may last several years.