Yugoslavia Factions OK Peace Talks : Secession: Leaders agree to a three-month moratorium and negotiations mediated by the European Community. Serbs and Croats battle.

BELGRADE, Yugoslavia —  Even as leaders of Yugoslavia and its constituent republics accepted a European Community peace plan Sunday, Serbs and Croats were pitted against each other in 10 hours of fierce fighting.

News service reports from the Adriatic island of Brioni, where the talks took place, said that negotiators, including three EC foreign ministers acting as mediators, agreed that all parties will begin talks Aug. 1. The talks are to cover every aspect of the future of Yugoslavia in an effort to avert the current threats of civil war and disintegration.

The talks will take place during a three-month moratorium by the breakaway republics of Slovenia and Croatia on further moves to implement their independence declarations of June 25, according to Foreign Minister Hans van den Broek of the Netherlands, one of the EC mediators.

The addition of the word further was a major concession to Slovenia, which had refused to repeal any of its sovereignty measures. Control of Slovenia’s 27 border crossings was a major sticking point between the federal government and the republic.

Under the accord, a compromise was reached on the border posts: Slovenian police will control the borders for now but will turn over revenue from customs duties to the federal government.

Van den Broek also said that under the plan, the EC will send a small group of civilian and military observers as soon as possible to monitor the current cease-fire between Slovenian forces and the Yugoslav army. The team will monitor fulfillment of all other aspects of the agreement, he said.

The accord, he added, also provides for the federal presidency to re-establish full control over the Yugoslav armed forces and for the return of all federal and Slovenian armed forces to their bases by midnight tonight (3 p.m. PDT).

Slovenia had been ordered by the federal presidency to turn over control of its international border crossings to Yugoslav authorities by noon Sunday. It had steadfastly refused to do so, claiming control of the frontiers had always been a matter for the republics, not the federal government or the army.

While the EC-brokered peace plan raised hopes, fighting erupted in several villages of northeastern Croatia on Sunday, pitting Serbs against Croats and drawing the federal army into a long-feared bloodletting.

Reports of casualties were contradictory, with the Yugoslav news agency Tanjug saying four people were killed and Croatian authorities claiming the death toll was in the dozens.

Belgrade Television showed ambulances screaming into the village of Tenja, where tanks and bullet-riddled cars were abandoned on the roadsides, houses smoked from mortar fire, blood was spattered on the sidewalks and at least two corpses lay on the main road.

The violence in Tenja and other ethnically mixed villages about 100 miles west of Belgrade followed warnings a day earlier by both Serbia and Croatia that a bloody civil war loomed over the deeply divided Balkan federation.

The deadly clashes shifted the focus of Yugoslavia’s escalating conflict to Croatia after more than a week of attempts to firm up a cease-fire in Slovenia, where 60 were killed and 300 wounded in battles with the federal army last week.

The four-day-old cease-fire appeared to be holding in Slovenia.

However, the federal army has been deploying troops and issuing threats on its own, raising the question of whether the Croatian head of the collective presidency, Stipe Mesic, actually wields much influence over the Serbian-dominated military.

It is unclear whether the federal army will abide by EC plan agreed to on Sunday.

The fighting broke out in Tenja and in other villages around Vukovar and Osijek after Croatian reservists moved in to rout Serbian extremists known as chetniks.

Croatian media claim that hundreds of chetniks have infiltrated their republic to help local Serbs in their armed struggle against Croatia’s secession from Yugoslavia.

Tanjug said that gun battles raged between Serbs and Croats for 10 hours. Tanks and troops deployed to the volatile region of northeastern Croatia moved into Tenja after the clashes broke out. Media reports indicated that the fighting intensified after the army intervened.

Zagreb Radio quoted the mayor of Osijek, Zlatko Krmaric, as saying the army was supporting rebel Serbs.

“The army has again sided with the chetniks who have been shooting at the national guard from behind armored vehicles,” the mayor complained in the broadcast.

Krmaric said there were “many injured and dead” among the Serbian nationalists, and a spokesman for the Croatian Defense Ministry in Zagreb made the same claim.

Federal troops deployed to the region in force on Wednesday, after a massive mobilization of Serbian reservists. The call-up, said to have involved 200,000, was aimed at creating an ethnically homogenous fighting force that could be depended on to carry out missions devised by the Serbian-dominated high command.

Belgrade Radio said the federal soldiers intervened to separate the combatants but halted after being attacked by mortar fire.

Federal troops and tanks of the Yugoslav People’s Army moved in to Serbian-populated regions of Croatia and Bosnia-Herzegovina on Wednesday, only a few hours after the chief of staff issued a menacing statement that many thought signaled a behind-the-scenes military coup d’etat.

Gen. Blagoje Adzic, an arch-conservative Serbian Communist, vowed to crush Slovenia’s moves toward independence, although tanks and troops have been deployed elsewhere.

Adzic’s ominous threat to deliver “a massive and rigorous military strike” against Slovenia has not yet been explained. It intensified speculation that the army has engaged in renegade behavior, since no federal authorization was given for the 180-vehicle deployment of heavy armor and the federal Defense Minister has distanced himself from threats of a strike.

Both Croatian and Serbian media have provided biased and often contradictory reports on the recent violent outbreaks that have killed at least 49 in the republic since May 2.

Serbia has threatened to go to war to prevent separation of the 600,000 ethnic Serbs who live in Croatia from the Serbian republic with which they are politically bound within the 73-year-old Yugoslav federation.