The UN's emergency coordinator in Pakistan, Jan Vandemoortele, said aid had reached some victims of the October 8 disaster but warned that complacency was a bigger enemy than the weather and the rugged terrain.

A UN official in charge of providing shelter, Darren Boisvert, also warned that 90 percent of the 420,000 tents handed out were not ready for winter, although survivors were strengthening them with plastic sheets and blankets.

"The situation remains very difficult and indeed we are on a knife's edge," Vandemoortele told a news conference.

The three biggest priorities were to provide heating for freezing families; corrugated iron sheets so quake victims can build their own shelter, and winterised tents, Vandemoortele said.

He said there were encouraging aspects to the aid effort but massive problems remained, adding: "We have got two versions of the story, of the glass being half full and half empty."

People were starting to rebuild thanks to government compensation and thousands of tents had been distributed, but many were not designed to withstand the bitter winter that began last weekend, he said.

Emergency food stocks were being built up, but rations had been cut so they could last longer. Schools had restarted, but many were in tents where students had to battle against the cold, he added.

He said that while there had been no disease epidemics and immunisation campaigns were underway, there had been a number of cases of pneumonia and diarrhoea.

Meanwhile funding for the UN's flash appeal of 550-million for emergency aid had increased over the last month but it was still only 41 percent funded after two months.

Vandemoortele said "nobody should be carried away" by the figures for how much aid had been handed out to surivors.

"Irrational exuberance about these numbers would be unwise, in fact it could be deadly," he added. "We need continued cash and cooperation to get the job done."

Vandemoortele added: "The worst enemies we face are not the mountains and not the winter, the worst enemies we face are complacency and pessimism."

Boisvert, who works for the International Office of Migration, told the conference that 90 percent of the tents "are not winterized".

But Vandemoortele stressed that most people were using blankets, tarpaulins and whatever else they could lay their hands on to bring their tents up to standard to get through the winter.

"When we say that 90 percent of tents are winterized, it does not mean that they are inadequate, the proportion of tents that is not adequate is much, much smaller," he said.

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