Doctors struggling with a constant flow of patients in a quake-ravaged Pakistani city warned on Saturday that the number of sick could swell dramatically in the coming weeks, as harsh weather creates conditions for pneumonia and other illnesses to spread.

A total of 234 patients with winter-related ailments were admitted within the past 24 hours, said Bashir Rahman, medical superintendent at the state-run Abbas Institute of Medical Science hospital in Muzaffarabad, one of the cities hit hardest by the Oct. 8 earthquake.

Seven had pneumonia, he said.

"The situation now is under control but in the coming days it could get worse, especially for people living at high altitude," he said.

Dr. Abdul Hamid of the Pakistan Islamic Medical Association, which runs a field hospital in Muzaffarabad, said 174 people with respiratory tract infections, flu, fever and pneumonia had been admitted in the past two days.

Fearing a second wave of deaths, soldiers and emergency workers have been racing to get food and proper shelter for the estimated 3.5 million people left homeless by the magnitude 7.6 quake that killed 87,000 people in Pakistan and India.

Most of the deaths were in Kashmir, the Himalayan territory divided between the two countries but claimed in entirety by both. Muzaffarabad is the capital of the Pakistan-controlled portion.

Winter's approach has begun to hamper relief operations to the region's more remote areas, reachable by helicopter in good weather. On bad days, mules are often the only way to get in.

Muzaffarabad's skies were cloudy Saturday, but relief helicopters were flying.

Pakistani soldiers are building 5,000 shelters a day. Aid workers say that most of the hundreds of thousands of tents that have already been distributed cannot give quake survivors adequate protection against the cold, and that sturdier corrugated iron shelters should be used.

The army has constructed about 30,000 such shelters.

Officials said they are also especially worried that hundreds of thousands of people who live at the higher elevations may be forced to come down to refugee camps as winter wears on, creating crowded conditions and possibly sanitation problems.

Darren Boisvert, spokesman for the International Organization for Migration, said 5,000 tents that are adequate for winter have been distributed to those above the snow line, and another 5,000 will be handed out by Dec. 12.

He acknowledged that officials are not certain how many people will need emergency help due to the remoteness of some stricken areas and are assessing the scale of damage.

"We are working from the top down," he said Friday at a news conference in Islamabad, Pakistan's capital.

Jan Vandemoortele, the U.N.'s top aid coordinator in Pakistan, said a "colossal job" lies ahead.

Vandemoortele said many villagers are choosing to stay put despite the hardships, and that no one will be forced to leave their homes.

But as the weather deteriorates, more people are expected to flow into the camps, he said.

"We remain on a knife's edge," he said. "It may get worse before it gets better."