GENEVA - UN weather experts said unusually low temperatures and heavy snowfall would soon hit areas of Pakistani Kashmir, jeopardising efforts to feed and shelter survivors of the South Asian earthquake.

Aid agencies renewed appeals for funds to keep open a lifeline to the millions left homeless in remote parts of the Himalayas by the October 8 quake, many of them injured.

"The situation is getting more and more desperate," said the United Nations Office for the Coordination of Humanitarian Affairs (OCHA).

The World Meteorological Organisation (WMO) said that winter was only three weeks away and initial reports suggested the weather would be unusually cold in the stricken mountain areas.

"An initial overview indicates that another harsh winter is approaching the earthquake-stricken areas. Snowfall is expected to considerably exceed the normal range, both in frequency and quantity," WMO spokesman Mark Oliver told a news conference.

Snow has already fallen in some remote districts, he said.

From December to February temperatures were likely to be "well below normal," said Oliver. "That means even day temperatures are likely to stay several degrees below freezing, especially in the mountainous areas," he added.

In January temperatures could plunge to minus 20degC at night.

The World Health Organisation warned there could be a second wave of deaths. "We cannot wait to see images of people freezing to death or dying of preventable disease before we act," said Ala Alwan, in charge of health action in crises at the WHO.

UN agencies said a major donors' meeting in Geneva this week had raised too little, and a huge cash shortfall threatened to ground helicopters and interrupt food supplies for survivors.

OCHA said it had received only $117.4 ($168.24) million, 21.3 per cent of the cash the United Nations had sought from the international community.

The donors' meeting produced pledges of only $16 million for an appeal for a sum that the UN increased this week to $550 million from $312 million as the full impact of the disaster and the needs of survivors became clear.

The response is "not enough", said OCHA spokeswoman Elisabeth Byrs. "We need money immediately to be able to reach people now, not in two to three months because people will be dead by then."

OCHA's latest estimate showed that up to 30 per cent of the areas affected have not been reached and it said this meant at least 200,000 people were not getting the aid they required.

The UN's World Food Programme (WFP) said it had sharply increased its estimate of the number of people needing aid to 2.3 million, of whom less than a fifth had so far been reached.

Its initial estimate of one million people was included in the original UN appeal. The WFP had sought $56 million but had received only 16 per cent of this and would probably need to appeal again, spokeswoman Christiane Berthiaume said.

"We need the money now to pre-position the food stocks before mountain roads are cut off, not in February," she said.