By Shaban Buza
PRISTINA, Yugoslavia, May 19 (Reuters) - The United Nations refugee agency, UNHCR, has warned of an exodus of up to 20,000 ethnic Albanians from southern Serbia if the return of Yugoslav forces to a sensitive area next to the Kosovo border is botched.
Eric Morris, the agency's Special Envoy in the Balkans, told Reuters in an interview he doubted whether enough measures had been taken to reassure the local ethnic Albanian population and calm their fear of Yugoslav state security forces.
Belgrade's forces are scheduled to move on Thursday into "Sector B" of a NATO-ordained buffer zone around the outside of Kosovo's border with Yugoslavia as part of an effort to end an ethnic Albanian guerrilla insurgency in the area.
"If it is not handled carefully, we will have conflict and if we do have armed conflict, we will have Albanians moving out and becoming displaced persons in Kosovo," Morris said.
"If there is any significant armed conflict... we can expect 15-20,000 people coming," he said, speaking in Kosovo's capital Pristina on Friday.
Morris said a central issue in the Presevo Valley area of Serbia bordering Kosovo was Albanians' fear of Serb forces.
Those forces acquired a reputation for brutality and atrocities among their enemies in Croatia and Bosnia and in ethnic Albanian-dominated Kosovo during the rule of Slobodan Milosevic.
NATO, however, has been anxious to bolster the reformers who ousted Milosevic as Yugoslav president in October last year and has been handing back parts of the five km (three mile) wide buffer zone to Yugoslav forces in the past few months.
Now only "Sector B" remains, a strip of land of land around 35 km long. It is currently held by a local ethnic Albanian "liberation army" which emerged at the start of last year. Yugoslav forces have pledged to show restraint when they go in.
MISTRUST SHOULD NOT BE UNDERESTIMATED
Morris welcomed efforts to address Albanian grievances, such as an agreement to establish a multi-ethnic local police force, but said he feared those steps may not yet be far enough advanced to reassure local people.
He said the UNHCR believed that at present "the confidence-building measures have not been sufficiently implemented".
"What we have said to a number of the people we see in Belgrade is: 'Do not underestimate the total mistrust that the Albanian civilian population has for your security forces'," Morris added.
Even low-level fighting when Yugoslav forces enter the zone could trigger enough fear to set off an exodus, he said.
The stance the guerrilla group will adopt remains unclear. Some commanders have vowed they will fight if Yugoslav forces move into Sector B, others have sounded more conciliatory.
The UNHCR, which has spent much of the past two years dealing with ethnic Albanians who fled Kosovo, now finds itself coping with an influx.
More than 18,000 people have sought shelter in Kosovo from a similar conflict in Macedonia, and more than 3,000 fled the Presevo Valley for Kosovo amid fighting last week.
"If there is not some real action on these confidence- building measures, there will be problems and then you will not have the conditions for the civil population to remain, much less return," said Morris.