The evacuations have gone ahead despite Nato's strong opposition

A UNHCR spokesman, Dennis Macnamara, said the agency had moved out several hundred Serbs.

"We don't choose to do that. But do we allow them to remain and be attacked, in some cases killed?" he asked.

"Some people we haven't evacuated and who wanted it have lost their lives in the last weeks."

Mr Macnamara warned that the UNHCR might soon undertake evacuations on a wider scale, because of growing threats from Kosovo Albanian gunmen.

The agency believes that only 50,000 Serbs remain in Kosovo - a quarter of the pre-war population.

The BBC's Orla Guerin: "Nato says it won't help the Serbs go"

A spokesman for the Nato-led peacekeeping force, K-For, said Nato strongly opposed the departure of Serbs, and would not assist or encourage the evacuations.

K-For on Monday reported a drop in the number of violent incidents for the third day running. But BBC Correspondent Orla Guerin says the fact that the UNHCR has been moving Serbs out of the province will be seen as a sign of failure for the international community.

Serbs return to Polje

But despite the fears, some 200 Serb railway workers arrived in Kosovo Polje on Monday - the largest known group of Serbs to return to Kosovo since June.

The UN fears that more Serbs could die

Many Serbs had fled the province to escape the wrath of Albanians infuriated by alleged atrocities by Serb forces who pulled out of Kosovo in June.

They were escorted by two armoured personnel carriers and a UN jeep. A few local Serbs awaited them at the railway station.

UN official Terry Stewart said the returning Serbs would start working after being registered.

"This is the biggest return of Serbs in the last six weeks. I hope that they will stay here."

Demonstrations called off

Kosovo Albanian leaders have meanwhile called off demonstrations at a bridge dividing the northern mining town of Mitrovica, which has been the scene of confrontations with French peacekeeping troops.

The protests were cancelled after a plan was drawn up to enable Albanian families to return to their homes in the Serb-dominated part of town across the Ibar river.

Angry demonstrators demanding that Albanians be allowed to return to their homes across the bridge engaged the French peacekeepers in often violent clashes over four consecutive days last week.

The Albanian mayor, Bajram Rexhepi, told a crowd on the south side of the bridge that about 25 Albanian families a day would be escorted back to their homes on the north side.

A total of 1,200 families were waiting to go back to the Serb-dominated sector, he said.

The Kosovo Liberation Army (KLA) - blamed for much of the anti-Serb violence in the province since Yugoslav forces withdrew - has backed the proposed agreement.

No-one 'out on the street'

Mary-Pat Silveira, the deputy UN chief in Mitrovica, said she hoped that some Albanian families could begin returning to the city this week.

She said the problem with the resettlement plan was that some of the apartments are now occupied by other displaced people, some of them Serbs, and officials have to find alternative shelters for them before the Albanians return home.

But she added: "We will not put people out in the street."