According to Albanian sources in Tirana, 23,000 Kosovans passed the border crossing of Morina in 24 hours.

"They're coming thick and fast," said an official of the Organisation for Security and Cooperation in Europe (OSCE).

Relief officials in northern Albania said the latest arrivals - in cars, tractors, trucks and on foot - were in the worst condition they had seen.

Children buried

Aid agencies are reporting the first cases of malnutrition among children crossing from Kosovo.

The news came as Nato claimed that Kosovo Albanians are being used to dig the graves of their slaughtered countrymen while men and boys are being put to work in coal mines in Pristina.

Relief workers say some refugees have told them they had to bury children along the road who were simply too weak to make the journey. Others bear injuries they blame on Serb security forces.

Mass airlift

Albania and the former Yugoslav republic of Macedonia face a massive influx of refugees fleeing the latest Serb attacks.

The BBC's Brian Barron: "A convincing picture of ethnic cleansing"

On the Kosovo borders 20,000 refugees entered Albania on Saturday, with 50,000 more estimated to be making their way on foot after the latest round of ethnic cleansing by Serb forces. Around 375,000 refugees have fled to Albania since the crisis began in March last year.

At least 4,000 refugees arrived in Macedonia on Friday, but Macedonian authorities have repeatedly expressed fears that the increasing numbers could upset the ethnic balance and political stability.

The United Nations says it may have to call for a mass airlift to move people out of the region.

(Click here for a map showing refugee movements)

Nato's aid operation in Albania is expanding, with military helicopters being used to take those suffering most to better equipped camps further south.

Many are forced to live in makeshift shelters

Most of the refugees have come from the town of Mitrovica, north of the Kosovo capital Pristina. They were herded out over the past few days by Serb forces, many wearing masks. Some said the Serbs had shot at them as they left.

The BBC's Rageh Omaar: The expulsion was methodical

Many families have been split up, and although new camps are being built, thousands are having to spend the cold nights without cover.

With more refugees fleeing Kosovo, the United Nations says it fears there will soon be no Kosovo Albanians left in the province.

Nato military spokesman Brigadier-General Giuseppe Marani said independent evidence backed up reports that many refugees were now being forced to dig graves for their slaughtered countrymen, wearing red-orange jackets to identify them as part of grave-digging parties.

He said the "gruesome" task involved digging "neat rows of graves facing Mecca".

Another "ominous" development was that men and boys were being taken and put to work digging coal from mines around Pristina which are source of most of Kosovo's electricity.