Pristina - Serb forces launched a widespread offensive in the west of Kosovo, attacking 40 villages in the province and sending thousands of ethnic Albanians on to the roads, aid workers and Albanian sources said.
The UN High Commissioner for Refugees said heavy shelling had trapped about 25,000 people, most of them women and children.
The spokesman, Mr Paul Stromberg, said representatives of the UNHCR on the scene had warned of a massacre if shells fell among the packed vehicles.