A UN team has arrived in Yugoslavia to investigate the extent of the environmental damage caused by the Nato bombing campaign.

The scientists will take soil samples and carry out other tests around oil refineries and factories which were targeted by allied attacks.

Nato's strategy of bombing industrial sites led to widespread panic about toxic fumes and poisoned rivers.

In some towns, people used homemade gas masks to protect themselves from air pollution.

Black clouds of smoke rising above oil refineries are some of the most enduring images of the war in Serbia.

Scare stories

Now that the war is over, experts are trying to separate scientific fact from scare stories.

The UN Balkans Task Force in Belgrade will carry out tests on the soil, air and water as part of the first objective assessment of the environmental consequences of the conflict.

They will begin their work on Tuesday at the Pancevo industrial complex, on the outskirts of Belgrade, before moving on to the oil refinery in Novi Sad and other major factories.

Sensitive mission

A full study of the impact of the bombing on the River Danube and on health in the region will take place in August.

The task force is taking a regional approach to environmental problems with experts travelling to Montenegro, Kosovo, Macedonia and Albania.

UN officials stress that their work is only at the assessment stage and no recommendations can be expected before September.

The UN team currently in Serbia is aware of the political sensitivity of its mission.

Western governments are making a firm distinction between humanitarian aid to Serbia, which they support, and reconstruction aid which they are ruling out as long as President Slobodan Milosevic is in power.

In response UN officials are stressing the humanitarian nature of the environmental mission.