Anthea Webb of the United Nations World Food Programme said: "Many of these people are living in open camps with only the clothes on their backs and no proper shelter.

"We're worried about pneumonia and hypothermia as well as the food situation."

The UN estimates that 265,000 people have been driven from their homes by fighting in Kosovo. As many as 50,000 of those displaced are thought to be living exposed to the elements.

The forecast is for even cooler weather

The temperature fell to 7°C on Friday night, and was even lower in the mountains, where many refugees fled to escape the Serb shelling.

"People are moving by tractor and by horse and cart. How they're going to get away, how we're going to get food to them is difficult," Ms Webb said.

The forecast for Kosovo was for even cooler weather overnight and near freezing temperatures in the mountains.

Lives threatened

International relief experts warn that the onset of cooler, wetter weather could begin to kill significant numbers of refugees living rough in remote areas of Kosovo, especially among the young, the old and the sick.

United States Assistant Secretary of State Julia Taft said on Thursday the international community had no more than six weeks to implement a crash programme of humanitarian assistance in Kosovo if the most vulnerable were to be saved.

She pledged to ask President Bill Clinton for "substantial" additional American funding to help alleviate the humanitarian crisis.

Victims of Serb shelling

The UN refugee agency says a 10-month-old baby was one of the victims of Serbian shelling of a village of Senik in south-west Kosovo.

A UN spokesman said the village was still burning when its team arrived.

Witnesses told them that at least 16 ethnic Albanian civilians had been killed.

The team also reported a large influx of refugees in nearby villages.

The Serbian authorities say they have regained control of a neighbouring area around the town of Dulje, about 35km the provincial capital, Pristina, after several days of fighting against the separatist Kosovo Liberation Army.