By David B. Ottaway -Washington Post Service-

THE HAGUE--The United States has warned Serbia that unless it cooperates fully in the prosecution of Serbian officers and officials responsible for committing war crimes in Bosnia, Washington will not vote in the UN Security Council to ease or lift the sanctions that have devastated Serbia's economy.

Madeleine K. Albright, the U.S. representative at the United Nations, who issued the warning, announced that the Clinton administration was turning over thousands of pages of previously classified testimony to the UN War Crimes Tribunal on alleged Serbian war crimes.

Excerpts from the first 1,000 pages of U.S. collected testimony from 400 former war prisoners and refugees were made available Sunday in the Hague. The material contains the names of scores of Serbian prison camp commanders and other officers and spells out the atrocities for which they were allegedly responsible.

The tribunal president, Antonio Cassese of Italy, said that the first trials of accused war criminals would probably take place in June. He said the initial defendants would be Serbs, Croats and Muslims, and he expressed confidence that at least some of those indicted could be apprehended by then.

Mrs. Albright also warned that the United States intended to consider interference by any of the three warring Bosnian factions in the delivery of emergency food supplies a violation of international law that should fall under the jurisdiction of the tribunal.

But her message was clearly aimed at Serbia and its Bosnian Serb allies who have been blamed by numerous UN resolutions for forced removals known as "ethnic cleansing."

"The United States will examine any effort to ease or lift sanctions in the context of whether there has been full compliance with, inter alia, Security Council resolutions relating to war crimes" and to "the delivery of humanitarian aid."