The United Nations Secretary General, Kofi Annan, said he was deeply disturbed by what he called atrocities committed by Serbian military and paramilitary forces against unarmed civilians in the Serb province.

A statement from the UN leader said: "They must not be allowed to repeat the campaign of ethnic cleansing and indiscriminate attacks on civilians that characterised the war in Bosnia."

The Security Council meanwhile called for humanitarian organisations to be given immediate and unimpeded access to all parts of Kosovo.

Thousands flee

Thousands seek refuge across the border

Eyewitnesses among more than 10,000 refugees from the conflict say Serbian forces have emptied their villages. Serbia says it is pushing back separatist forces despite its patrols coming under repeated attack.

As the offensive continues, tens of thousands of Kosovo Albanians continue to flee into Albania - many of them women and children.

Andrew Harper of the UN High Commissioner for Refugees says many of them are in a very poor state.

"They have been bombarded physically and spiritually for the last month or so. The majority of those entering Albania are still women and children.

"We transported an eight-months pregnant woman who had been walking for the last 19 hours. She was obviously in a very poor state.

"There were new-born babies who had been born in the mountains in the forest. Their mothers and their fathers were very distressed. When they left Kosovo most of them brought nothing with them. If they did, they are the lucky ones.

"Some just arrived with nothing. When the shelling started they were so scared they didn't even put on their shoes."

Deepening crisis

Meanwhile the international community is increasing its efforts to force an end to the deepening crisis in Kosovo.

More than 250 people have died since March 1 in escalating clashes between Serbian government forces and the Kosovo Liberation Army, the armed wing of the Albanian independence movement.

Ethnic Albanian leaders have accused the Serbs of laying siege to areas of Kosovo and of attempting "ethnic cleansing" as thousands of ethnic Albanians escape the fighting into other areas of the province or into neighbouring countries.