The UN's emergency relief chief is to fly to Brussels to appeal to Nato to send more helicopters to help victims of the South Asia quake.
The UN warns tens of thousands more could die without Nato help
Jan Egeland has urged members of the 26-nation alliance to launch "a second Berlin airlift" to rescue those left without shelter as winter approaches.
The US has said the first of 20 more of its helicopters will arrive next week.
Mr Egeland's appeal follows the UN's admission that the quake is the worst logistical nightmare it has ever faced.
The UN says the shortfall in aid for victims of the South Asian quake has made the relief situation worse than after last December's tsunami.
Nato began flying in 900 tonnes of aid on Thursday, but Mr Egeland said a massive airlift was also needed to bring people out of remote areas.
Pakistan says nearly 50,000 people died in areas under its control.
Local officials put casualties far higher, and the number is expected to rise. At least 1,400 others died in Indian-administered Kashmir, officials say.
An estimated three million people remain homeless or without safe shelter.
Mr Egeland said an airlift was needed on the scale of the Berlin blockade of the 1940s, when Allies flew in supplies to the divided city in communist eastern Europe.
He said aid had to be sent in and tens of thousands of homeless and injured people flown out of remote regions before winter set in - or tens of thousands more lives could be lost.
"I have asked Nato and I will reiterate that appeal: think bold, think big, think creatively," he said ahead of Friday's meeting in Brussels.
"I don't know how you evacuate hundreds of thousands of people from the Himalayas, but the most effective military alliance in the world should be able to."
Nato Secretary-General Jaap de Hoop Scheffer said: "You must rest assured that Nato fully realises the gravity of the situation. Nato will act accordingly."
However, US vice-admiral John Stufflebeem, who commands the NATO rapid reaction force, said very few of the light helicopters needed were available.
Ten thousand tents will be flown to Pakistan over the next few weeks, although the UN has warned there may not be enough winterised tents in the world to meet the needs of the earthquake victims.
Heavy duty tent designed for long-term use by a single family
PVC groundsheet sewn onto the sides for wind proofing and to retain warmth
Some types are designed to accommodate cooking stoves
ICRC estimates that 30,000 such tents are required in Pakistan
The US said its extra helicopters would arrive in Pakistan next week, giving a significant boost to the 60 currently operating in the region.
Mr Egeland said only $86m had been pledged of the $312m the UN had asked for to fund the relief operation - and far less actually received in cash.
"The world is not responding as it should," he added.
Earlier, UN Secretary General Kofi Annan called for the global relief effort to be increased to help those made homeless by the 8 October quake and facing the fierce Himalayan winter without shelter.
"That means a second, massive wave of death will happen if we do not step up our efforts now," he said.
He called upon top international representatives to attend a UN-sponsored donors conference in Geneva, Switzerland, next week.
While 92 countries had helped nations hit by last year's tsunami, only some 15 to 20 countries had responded to the quake, Reuters news agency quoted Mr Egeland as saying.