Amid warnings that help is barely reaching thousands of shelterless or injured survivors in mountainous areas of Pakistani Kashmir, the UN has only received a fraction of its 312 million dollar (259 million euro) appeal launched nearly three weeks ago.

That appeal is likely to be revised in the coming days, aid sources said.

The United Nations tally so far includes 68 million dollars in cash and another 35 million dollars in pledges from donor governments for six months of emergency relief funding.

The world body warned this week that bad weather in coming days was likely to hamper crucial helicopter flights in the region, while winter snowfall was expected to take hold in three weeks.

"If we do not reach all the most seriously injured in isolated villages within two weeks, we will face a second wave of deaths," UN humanitarian affairs spokeswoman Elisabeth Byrs told AFP.

Some 70,000 people in Pakistan were injured and more than 800,000 left without shelter after the 7.6 magnitude earthquake levelled towns and isolated villages in northern Pakistan on October 8.

Annan is, unusually, due to take part in the meeting to press the case for a speedier response to the plight of the victims, alongside his emergency relief chief Jan Egeland and other agencies including the Red Cross.

Sixty-five countries, including Pakistan, have so far registered to take part, Byrs said.

Top level participants are expected to include French Foreign Minister Philippe Douste-Blazy, his Swiss counterpart Micheline Calmy-Rey, Britain's Overseas Development minister Hilary Benn and Andrew Natsios, the head of the US government aid agency (USAID).

"We are very satisfied with the response. From the signs we have it's lining up very well," Byrs told journalists.

"We'll take stock of the situation and the humanitarian response and look at the problems we need to confront as swiftly as possible. States will have a chance to announce their funding aims," she added.

Pakistani minister of state for economic affairs, Hina Rabbani Khar and presidential economics advisor Salman Shah are due to lead the country's appeal to rehabilitate thousands of injured and rebuild the region.

UN officials believe the shortfall is slowing down the relief effort when they are facing a race against time.

However, aid sources indicated that overall funding and pledges, including bilateral assistance from countries offered directly to Pakistan, has reached 718 million dollars.

Some 164 million dollars has been committed both within the UN-coordinated appeal and as bilateral aid, the sources said. Another 554 million in pledges have been made.

The British aid charity Oxfam said Tuesday that rich countries were not giving enough for Pakistan.

About 100 helicopters were ferrying aid around the Himalayan region and the top priority for donors now should be shelter equipment including tents, Byrs said.

"We'll ask for a few more helicopters, but it's no longer the most essential thing. Now it's shelter, shelter, shelter," she added. Some 200,000 tents are "in the pipeline" according to the UN.

The UN refugee agency said a chartered Boeing 747 cargo plane able to carry 76 tonnes of supplies per flight was joining its NATO-run airlift of supplies into Pakistan, which was limited to 10 tonnes per flight.

"This will considerably shorten the amount of time that we need to get the remaining 600 tonnes of supplies from our warehouses in Turkey down to Pakistan," said Jennifer Pagonis, a spokeswoman for the UN High Commissioner for Refugees.

"Certainly this is a race against time and the weather and we hope to get our material on the ground as soon as we possibly can," Pagonis added.