By Jacky Rowland in Belgrade

The United Nations chief refugee official, Sadako Ogata, has expressed doubts that Serb refugees from Kosovo will be able to return to their homes soon.

Mrs Ogata was speaking during a tour of Serbia, where she visited collective centres for Serb refugees from Kosovo and Croatia.

Serbia hosts the largest refugee population in Europe, with more than 700,000 refugees from the wars in the former Yugoslavia.

Mrs Ogata gave a stark assessment of the position of Serbs in Kosovo. The security situation in the province, she said, was not one in which the UN refugee agency could promote returns.

She said there were still people fleeing.

Her remarks are the latest acknowledgement by the international community of its failure to reassure and protect Serbs and other ethnic minorities.

More than 200,000 people have fled Kosovo since Nato-led peacekeeping forces arrived last June.

Mrs Ogata was speaking during a visit to refugee centres in two towns in Serbia. She met new refugees from Kosovo as well as long-term refugees who fled the war in Croatia.

Serbia is struggling to support a refugee population of higher than in any other European country.

A Serbian refugee official complained to Mrs Ogata that political conditions were being attached to the issue of humanitarian aid.

The UN High Commissioner is on a two-week tour of the Balkans, including Croatia, Bosnia, Serbia and Kosovo.

She has expressed optimism that Serb refugees from Croatia may now find it easier to return following the election of a new Croatian Government.

But elsewhere in the region the situation looks less promising. In Bosnia there are still some 800,000 displaced Serbs, Croats and Muslims four years after the end of the war.