serb officials have said that strikes by the North Atlantic Treaty Organisation's ( nato) forces on chemical plants and refineries around Belgrade could cause an ecological disaster.

Civil defence authorities said they have asked the residents of two districts near the Pancevo industrial complex, northeast of Belgrade, to evacuate. Serb officials said the nato bombings also caused an oil spill 15-20 km long in the Danube River. Officials downstream in Bulgaria said nothing had been spotted, so far, and the only reports in the Romanian media were those picked up from Yugoslavia.

Yugoslav environment minister Jagos Zelenovic said the repeated nato attacks had heavily damaged Pancevo's refinery, petrochemical plant and fertiliser factory and were causing a cross-border environmental hazard. "The spreading of harmful, dangerous, inflammable and explosive materials used in this complex has polluted the atmosphere, groundwater, rivers, lakes and water supply of the wider region,' he told a news agency.

"The effects of this pollution not only go across borders but these are long-lasting substances and carcinogens,' he said. nato has said it was hitting refineries and other strategic industries to cripple Yugoslavia's ability to wage war against the ethnic Albanian majority in the southern Serbian province of Kosovo.

Reporters taken on a tour of the Baric chemical complex southwest of Belgrade at Obrenovac said plant officials told them it produced hydrochloric acid for civilian use. A plant official warned that there was a serious risk of acid being released into the Sava River.