The fresh problems add to the task of international rescuers, who are already racing against the Himalayan winter to provide shelter and food for the three million people left homeless by the October 8 disaster.

"There is a major challenge on our hands now, particularly so people are not exposed to the elements in the next few weeks and months," United Nations spokesman Ben Malor told AFP.

The UN has repeatedly warned that cold weather could cause a second disaster among the tens of thousands of people living either in sprawling, squalid tent camps or in the ruins of their homes high in the mountains.

More than 420,000 tents have been handed out to quake victims so far, but Malor said relief workers were trying to "winterise" the 90 percent that an aid agency estimated were not designed to withstand the freezing conditions.

Another priority was to get corrugated iron sheeting to those not living in tents to create roofs for their makeshift shelters, Malor added.

The aid effort also faces a perennial problem, namely a lack of cash, especially for helicopters to reach cut-off areas. A 550-million-dollar UN emergency appeal is only 41 percent funded after two months.

But the deaths of seven Pakistani quake survivors, four of them children, in a tent fire this week had highlighted a further need -- for safe and efficient heating systems to guard against the cold, the UN said.

UN Children's Fund doctor Imran Raza, who is working in the quake zone, said that agencies were trying to bring in stoves safe to use in tents in a bid to prevent similar accidents.

"But in the meantime, everyone is concerned that, with the coming winter, there may be other incidents like this," Raza said in a statement.

"It's really sad when someone survives the earthquake only to end up dying in a fire."

The UN's Malor said efforts were underway to better organise sanitation and fire safety in the tent camps.

Meanwhile international experts are monitoring at least two huge lakes in Pakistani Kashmir which were created by the earthquake and are now threatening to flood nearby villages.

Military spokesman Major General Shaukat Sultan was quoted by state media as saying that the lakes were formed when streams were blocked by landslides and were now rising by 60 centimetres (two feet) a day.

One of the lakes near Haitian Bala, outside the devastated Pakistani Kashmir capital of Muzaffarabad, is about 100 metres wide and 25 metres deep, and the other is around 60 metres wide and 15 metres deep, he added.

"The situation is not serious at the moment, but with the passage of time it could trigger a flood during the rainy season and it could hit our settlements," local resident Abdul Ghafoor told AFP.

"There is a lot of concern," added the UN's Malor.

In Indian Kashmir, where more than 1,300 people died in the disaster, survivors were, meanwhile, awaiting a visit by Sonia Gandhi, chief of India's ruling Congress party.

She was shunning celebrations for her 59th birthday on Friday to travel to the quake-hit Poonch, Baramulla and Kupwara regions, the Press Trust of India news agency quoted her office as saying.

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