A United Nations team has begun work in Serbia to assess the damage to the environment caused by the Nato bombing.

It is the first UN mission to Belgrade since the bombing began on 24 March.

The team, which includes the UN Environment Programme's senior policy advisor, Bakary Kante of Senegal, arrived in the Serbian capital two days ago.

It has been sent by the UN Secretary-General, Kofi Annan, and is led by one of his key aides, Sergio de Mello, responsible for humanitarian affairs.

The team, set up jointly by UNEP and the UN Centre for Human Settlements (Habitat), has several aims:

• To collect data on damaged and destroyed hazardous installations such as chemical plants and refineries, and also on homes and infrastructure
• To research both actual and potential environmental impacts - soil and water pollution, acute air pollution, and damage to ecosystems
• To collect information on the state of the environment in Yugoslavia before the war began.

It will be meeting the environment minister, officials and plant managers.

The UN says the team's ultimate goal "is to obtain information from the Yugoslav authorities on their needs for specific assistance".

Team leader Sergio de Mello in Belgrade

It says it is important for the team to visit Pancevo, on the outskirts of Belgrade, where a big oil refinery and petrochemical and fertiliser plants have been bombed repeatedly.

The UN quotes Yugoslav sources as saying that "a large amount of oil and toxic chemicals has polluted the Danube, as a result of attacks on Pancevo"

Another destination for the mission is the city of Novi Sad, where oil depots and factories are reported to have been hit.

Dioxin worry

It has also been advised to visit Baric, where a plant using toxic chemicals is said to have been hit, and Nis, where factories have been bombed.

There is particular concern over the probable release into the air of dioxins, one of the most toxic sorts of poison known.

They are given off in fires, and accumulate in body fat, causing birth and genetic defects and infertility.