International experts invited by the United Nations to assess the environmental damage caused by the Balkan war have arrived in the northern Serbian city of Novi Sad.

The experts are working for the Balkans Task Force (BTF), a joint initiative of the UN Environment Programme (Unep) and the UN Centre for Human Settlements (Habitat).

The task force is chaired by a former environment minister of Finland, Pekka Haavisto, who has said the aim is to produce "a neutral and scientifically credible report on the situation".

White fog cloud

The team has already visited the Pancevo industrial complex, 15 km from Belgrade, which was heavily bombed.

The town contains an oil refinery, a fertiliser factory and a chemical plant. A raid in April hit storage tanks which released large amounts of vinyl chloride monomers (VCMs) into the air.

Pollution affects both air and water

The VCMs, used for making plastics, caught fire, producing a white fog which Pancevo's mayor, Srdjan Mikovic, said rolled across the town.

VCMs are carcinogenic. Soon after the raid, the Pancevo Institute for Health Protection recorded concentrations more than 10,000 times above safe industrial levels.

Thousands of tonnes of crude oil and refined products are said to have burned off after the refinery was hit. Officials have told local people not to eat vegetables grown round Pancevo, or to eat fish from the Danube, where chemicals released by the bombing ended up.

They are said to have included sodium hydroxide, nitric acid and 100 tonnes of mercury. The head of the town's environmental protection department, Milan Borna, said: "The full extent of the damage will show in coming years".

Oil leaks

"We fear that the worst effects may be degenerative changes in future generations."

The UN experts have gone to Novi Sad to assess the damage caused by the bombing of the refinery.

UN team members in Pancevo

They are taking samples, seeing how much of the oil was burnt, and trying to judge how much leaked into the groundwater.

Some of them are to return to Pancevo on 25 July for further investigations there. They are working with a similar team of experts, the Focus group, sent by the governments of Switzerland, Austria, Greece and Russia.

A Unep spokesman, Robert Bisset, said the BTF team was getting all the co-operation it needed from the Serb authorities.

"We ourselves decide where we want to go", he told BBC News Online. "And wherever it is we decide on, the Serbs are giving us full access."