Croatia Serbs Agree to Pact, but Government Is Silent : Balkans: U.S. ambassador conveys rebel leaders’ acceptance. Both armies remain on full alert.

ZAGREB, Croatia —  A last-ditch American peace initiative won apparent acceptance from rebel Croatian Serbs on Thursday but a cold, hard stare from a Croatian government poised to attack the Serbs with 100,000 troops, a move that would launch a new Balkan war.

“We see no reason for war at this time,” said U.S. Ambassador Peter W. Galbraith, standing on the doorstep of the presidential palace after meeting with Croatian President Franjo Tudjman. Galbraith relayed to Tudjman the rebel Serbs’ agreement to five Croatian demands that would end a rebellion and re-integrate a former Yugoslav republic torn by ethnic strife.

While diplomats were cautious, there was hope that the agreement could at least delay a war that has looked imminent in recent days. There was no immediate response from the Croatian government to the American initiative, but one presidential aide said privately it seemed a Serb ploy to buy time.

The Croatian Security Council met late into the night Thursday while the official Croatian media cold-shouldered both the American initiative and similar agreements accepted by the rebel Serbs at U.N.-sponsored talks in Geneva.

“The Croatians got what they wanted. The question is whether they will take ‘yes’ for an answer,” Galbraith said after his meeting with Tudjman.

The United States, major European powers and the United Nations were all pressing to win Croatian acceptance of the rebel concessions and avert war, diplomatic sources said.

Tensions lay heavy, though, along a cease-fire line between Roman Catholic Croatia and lands in the Krajina region seized by the secessionist Serbs in 1991 when the Yugoslav federation disintegrated. The war and its aftermath left 10,000 people dead, 270,000 driven from their homes and a third of the country in rebel hands.

Both Croatia and the Krajina Serbs are fully mobilized and have virtually their entire armies in the field. U.N. spokesman Christopher Gunness said Croatia had at least 100,000 troops in attack positions and the Krajina Serbs had about 50,000 troops dug in facing them.

“Our assessment is that Croatian forces are either at or very soon approaching their optimum deployment. They are battle ready and poised for offensive actions,” Gunness said, describing the situation as “highly volatile.”

Fifteen thousand to 20,000 Croatian soldiers, backed by tanks and heavy artillery, were at launch positions around the front-line town of Sunja, 50 miles southeast of Zagreb, the Croatian capital, Gunness said.

With the rebel Serbs’ self-declared capital of Knin the obvious target of any invasion, U.N. observers also reported Croatian troops ready to strike from positions in Adriatic coastal areas and from west-central Bosnia, where they captured two key towns from Bosnian Serbs in recent days, cutting supply lines to Knin.

Military sources say the Croatian army, which includes more than 60,000 conscripts, cannot stay at maximum alert indefinitely; it will either have to attack or stand down within a few days, they said Thursday.

On Wednesday, Galbraith flew to Belgrade, the Serbian and Yugoslav capital, to meet with Milan Babic, the Krajina Serbs’ “foreign minister.” Babic agreed to five points, Galbraith said, “that substantially fulfill the conditions of the Croatian government.”

The Krajina Serbs said they would immediately withdraw their troops helping to besiege the Muslim Bihac area of neighboring Bosnia-Herzegovina. The Serbs made the same vow to U.N. special envoy Yasushi Akashi in Knin last weekend but did not keep it, U.N. spokesmen said.

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Babic also told Galbraith that the rebel Serbs will: agree to immediately open an oil pipeline to Croatia through their territory; accept U.N. border monitors; and allow reopening of the Zagreb-Split railroad through Knin.

Critically, the Krajina Serbs also agreed to re-integration into Croatia under the terms of a U.S.-brokered plan that would grant Serb communities substantial self-government and high-profile international human rights guarantees in exchange for their acceptance of Croatian sovereignty.

Galbraith called the accord “very constructive” and a “very significant change” in the rebel Serb position. He attributed the shift to what he called “new realities” introduced by the successful Croatian sweep into the Livno Valley of Bosnia with the consent of the Bosnian government.

There, ongoing military action relieved pressure on the Bihac pocket, which had been under assault simultaneously by Croatian Serbs, Bosnian Serbs and rebel Muslims. At the same time, by cutting a key supply road, the Croatian success underlined the vulnerability of the Krajina Serbs.

A Krajina Serb negotiating team in Geneva agreed Thursday to substantially the same set of accords as Babic at a meeting sponsored by U.N. mediator Thorvald Stoltenberg, but the Croatian side demurred, a U.N. spokesman said.

Akashi also won concessions from the Krajina Serbs in a weekend visit to Knin, but his efforts were dismissed by Croatia.

In Washington, President Clinton said the United States is concerned about the war widening, although he was careful to avoid saying anything that might be interpreted as criticism of the Croatian army’s operations around the enclave of Bihac.

“We have cautioned the Croatians about widening the war,” Clinton told reporters. “We understand their desire to relieve the pressure on Bihac. And, of course, that is a commitment the United Nations has made as well.”

Times staff writer Norman Kempster in Washington contributed to this report.