The British-based agency reported that people in some communities have said they are digging graves before the ground freezes in anticipation of the deaths that winter may bring.
"There is a real danger that this unprecedented natural disaster will be followed by a manmade one," Farhana Faruqi Stocker, Oxfam's Pakistan country director, said in a statement. "The international community must work together and work faster to fulfill its promise to prevent further deaths."
Reporting from Islamabad, CBS News correspondent Mark Phillips finds the country's medical system is overwhelmed and lacks the means
to treat the thousands of injured survivors, especially those with spinal injuries,
Doctors say funds are needed to bring in more surgical supplies or to fly the injured out for treatment. Without that, Phillips reports, the consequences for those lying immobile and untreated are inevitable.
"Under these hygienic conditions, that means a high risk of infection, septicemia and then renal shut down, cardio-respiratory collapse and
death," Dr. Syed Husaini tells Phillips, referring to the cramped conditions in many Pakistani hospitals.
Oxfam said the United Nations has received commitments for only 40 percent of its appeal for quake aid, and that much of the money which has been promised has yet to arrive.
The Oct. 8 quake killed at least 87,000 people and left 3.5 million homeless in northwest Pakistan and Pakistani Kashmir. Aid workers have been racing against time to get aid and suitable shelter to the needy.
Pakistan's army said Saturday it has started replacing the regular tents that many refugees are using with winterized ones, especially in the highlands, where nighttime temperatures already are dropping below freezing.
Pakistan has distributed more than 600,000 tents, but the United Nations has said most are inadequate to face the harsh conditions to come. Forecasts call for the season's first heavy snow and rains to lash the area next week.
Survivors in many areas have have been demanding tents donated from abroad, including the United States, China and Iran, complaining that locally manufactured tents were of poor quality.
Army spokesman Maj. Farooq Nasir would not say how many tents would be replaced, but said troops are working at a brisk pace, already building 50,000 winterized shelters.
"Our soldiers are reaching far-flung areas on foot to deliver aid to survivors while we are continuously using helicopters to provide tents, clothes, food and even corrugated sheets to them," he said.
Nasir said people living on mountain tops in remote villages were reluctant to come down to refugee camps at lower levels although aid agencies say some have started moving lower and many more were expected to migrate. An estimated 400,000 people have been living at above 5,000 feet. Oxfam said some feel compelled to stay where they are, in part to look after their land and livestock.
The quake continues to cause problems. Nasir said eight families have been evacuated from the village of Chekar, where landslides caused by the magnitude 7.6 quake has created two huge lakes where the water level has started rising.
Geologists fear that any breach in reservoirs would trigger flash floods and might cause severe damage to dozens of villages and some bridges along the Jehlum river.
Pakistan largest newspaper The News quoted the country's top relief official, Maj. Gen. Farooq Ahmed Khan as saying that the quake created reservoirs that have to be drained carefully to avert threats to nearby villages.