Leaders of Kosovo's ethnic Albanian and Serbian communities appealed today for an end to the violent revenge-taking by ethnic Albanians that continues to plague this battered province three weeks after the arrival of NATO peacekeepers.

The call for calm, issued at the urging of the U.N. representative here, came only after seven hours of squabbling over wording to satisfy each side's sense of its suffering. The haggling highlighted the deep mistrust between the overwhelming ethnic Albanian majority in the province and the Serbs who were in charge until their forces were defeated and forced to withdraw by NATO's 78-day bombing campaign.

"We urge all Kosovo inhabitants, whether of civilian or military status, to refrain and to actively discourage others from any acts of violence against their neighbors," read a statement by members of a rebel-led ethnic Albanian interim government, the Serbian Orthodox Church and Serbian groups that oppose the government of President Slobodan Milosevic in Belgrade. "Such actions are unacceptable . . . those responsible will be brought to justice." Kosovo is a province of Serbia, the dominant republic of Yugoslavia.

No representative of the Serb-led Belgrade government was invited to today's meeting, U.N. officials said, although the former governor of Kosovo remains in the province.

The statement is to be publicized by local media. But it is uncertain whether the appeal will abate the daily attacks on Serbian civilians and property by ethnic Albanians returning from exile to find their homes destroyed and many of their relatives in graves after the campaign of repression and expulsion waged by Serb-led Yugoslav security forces during the war.

In the northern Yugoslav city of Novi Sad, thousands of Serbs clamored for Milosevic to resign in the second antigovernment protest in Serbia this week, the Associated Press reported. A banner at the protest read "Down with Milosevic!" and decried the lack of utilities and transportation. About 10,000 anti-Milosevic demonstrators rallied Tuesday in the central Serbian city of Cacak.

In Kosovo, U.N. officials clearly are worried that their efforts to sustain a multiethnic province, girded by a new judicial system, are fraying quickly, particularly because of the continuing exodus of fearful Serbs. Since NATO-led peacekeepers arrived June 12, at least 70,000 of the province's 200,000 Serbs have fled north in fear, U.N. officials said. And just this week, Serbian legal professionals who agreed to participate in a new legal system, a keystone of the U.N. reconstruction effort, warned that they, too, will leave unless security improves.

The Serbs "raised doubts about the wisdom for them to participate in any political process . . . until the security issue was addressed," said Sergio Vieira de Mello, special representative of the U.N. secretary general, in a meeting with reporters.

Key legal questions on satisfying the desire for justice felt by ethnic Albanians also remain unresolved. Officials with the international war crimes tribunal have said it will be difficult to investigate and prosecute every one of the numerous atrocities committed by Serbian forces in the past three months. Yet ethnic Albanians, many of whom are guarding the remains of their dead for forensic examination, expect no less.

What role, if any, the new criminal system being set up by the United Nations could play in cases that the war crimes tribunal cannot handle is also unresolved.

U.N. officials had hoped for a relatively quick meeting today leading to a straightforward condemnation of violence. But the two sides bogged down in arguments comparing ethnic Albanian revenge attacks on Serbs in the past three weeks and the Serbs' terror campaign of the previous three months, a U.N. official said.

In the end, the joint statement said "both sides condemn the crimes of the Milosevic regime in Kosovo," adding that there is no such thing as a natural hatred between the peoples of Kosovo.

Serbs -- and some Western officials -- have also complained that international peacekeepers have been inconsistent in their willingness to crack down on lawbreakers, including members of the rebel Kosovo Liberation Army. While British forces have sought with vigor to enforce the rule of law in the region of Kosovo for which they are responsible, the complaints say French and Italian forces have been lax, contributing to the escalating tension.

Vieira de Mello appointed nine judges and prosecutors Wednesday, including three Serbs. But he said that after the ceremony, in a private meeting, the Serbs told him: "Don't be surprised if in a couple of days we're gone."

The judges today began hearing the first of 221 cases brought against people arrested by peacekeepers.

According to Djordje Aksic, a former judge of the Yugoslav Supreme Court who is on the U.N. advisory body appointing judges and prosecutors, one Serbian judge who agreed to serve after initially fleeing returned this week to Pristina to find his apartment occupied by ethnic Albanians. Aksic also said that when he went to the provincial border between Kosovo and Serbia proper to pick up the judge, he saw five other former members of the bench leaving the province. They said they would not return.

"I was moderately optimistic that we could have a multiethnic Kosovo, but now my prognosis is very, very pessimistic," said Aksic, who resigned from the Yugoslav Supreme Court because of his unhappiness with the country's direction under Milosevic.