ISTOK, Yugoslavia (AP) _ A U.S.-backed plan to start resettling Serbs in Kosovo soon has U.N. officials fearful that events are moving too fast and could unhinge efforts to calm the province.

They note that exhumations of mass graves are expected to resume this week, ethnic Albanians are facing political trials in Serbia and relations between ethnic Albanians and Serbs remain strained at best.

Some U.S. officials, speaking on condition of anonymity, also have expressed alarm over the potential for a surge of revenge attacks.

Diplomats working in the U.N.-led Kosovo administration said Bishop Artemije, a moderate Serb leader, got approval for the resettlement plan when he met with Secretary of State Madeleine Albright in Washington in February.

Moderate Serb leaders argue that resettlement must begin to silence criticism by Serb hard-liners who say the moderates have betrayed Kosovo's dwindling Serb community. Only about 100,000 Serbs are believed to be in the province now, about half the number before the Kosovo conflict.

The climate does seem to be turning slightly more peaceful. Although Serb-Albanian hatreds still lead to frequent killings, moderate Serbs joined ethnic Albanian leaders Wednesday in urging tolerance, an unusual mutual gesture of conciliation.

The U.S.-supported proposal calls for 700 Serbs to be settled in the village of Osojane as early as next month, and there is also a vaguer U.N.-sponsored plan to bring back 20,000 people.

Opponents of the idea contend the effort is motivated by political reasons _ to demonstrate to skeptical voters in the NATO nations that the alliance's bombing of Yugoslavia was a good idea and that things are turning out all right in Kosovo.

``We have a pressure to prove that everything was done for the right reasons and that there has been a success. A success would be the large-scale return of people,'' said Paula Ghedini, a spokeswoman for the United Nations refugee agency.

In Istok, close to the desolate and shattered Serb village of Osojane, there are doubts a return will work just now.

``It could be dangerous,'' said Martin Dvorak, the U.N. administrator of Istok, a mountain town of about 7,000 people in western Kosovo. At the same time, he said, he understands ``the need to see visible progress.''

U.S. officials appear to be hoping to get support for the resettlement plan from Januz Januzi, an Albanian activist and fighter for the disbanded Kosovo Liberation Army who spent 10 years in Serbian jails.

That may not be likely. Januzi's overtures of reconciliation sound a rare positive note in the province and he has said Serbs who did not commit abuses against Albanians have a right to return. But he also says that ``first a period of reconciliation is necessary.''

Januzi says it will take ``two, three or four years'' for hatreds to die down sufficiently to permit the safe return of Serbs.

That is too long for the moderate Serbs who recently rejoined Kosovo's U.N.-led administration to press for repatriation of Serbs.

``If they don't return, we won't have anything in our hands to say (cooperation) is profitable,'' said Father Sava Janjic, a spokesman at the 14th century Gracanica monastery, the unofficial base for the moderates.

He said large-scale returns would ``shut the mouths'' of both the government of Yugoslav President Slobodan Milosevic and Serb hard-liners in Kosovo, both of which oppose cooperation with Kosovo Albanians.

In Serbia proper, where more than 100,000 displaced Serbs crowd refugee camps and other temporary quarters, impatience is building. On Wednesday, some 500 Serbs rallied in Kraljevo vowing to go back.

In the Kosovo village of Crkolez, home to a few hundred Serbs and ethnic Albanians, a half dozen Serb pig farmers sharing pear brandy around a large table said returns must go ahead.

``It is going to be a big step for the United Nations, a big step for the Serbs and a big step for ethnic Albanians. But it is a big mistake if it doesn't succeed,'' said Zikica Belosevik.

Fearing reprisals from ethnic Albanians, two-thirds of Crkolez's Serb residents fled after Yugoslav forces pulled out of Kosovo last June.

Hashim Thaci, the former guerrilla leader who is now perhaps the most influential Albanian politician in Kosovo, said he agrees ``in principle'' to a multiethnic society. But he cautions against haste.

``We have to work at building institutions. We have to bear in mind mass graves, about 5,000 ethnic Albanians kept as hostages in Serb jails,'' he said in an interview. ``The return of Serbs won't be beneficial if it is rushed.''