AFTER Slovenia and Croatia, Macedonia is now taking its turn at seeking independence from Yugoslavia, a move that complicates the European Community's efforts to settle peacefully the breakup of the six-republic Balkan federation.The acrimonious words of Yugoslav leaders, speaking at Saturday's opening session of an EC-sponsored Yugoslavia peace conference in The Hague, had barely reached audiences at home when voters in the southern republic of Macedonia were casting ballots Sunday in an independence referendum. Although the vote-counting was not complete as of Monday afternoon, pre-referendum polls left little doubt about the pro-independence outcome. A strong independence push in Macedonia risks creating a conflagration in Yugoslavia that Europe fears and is working to avoid. This ancient region, with a strong Muslim minority, spills over into Bulgaria, Greece, and Albania, and many Serbs consider it southern Serbia. Macedonia's Albanian, Bulgarian, and Serbian neighbors covet parts of the republic, while Greece doesn't want an independent Macedonia because it fears a general questioning of the region's post-World War II borders. This latest Yugoslav wrinkle further illustrates why the European Community is anxious to address what one EC official calls "an atom bomb in our own backyard." (Balkan fallout, Page 5). British Foreign Minister Douglas Hurd used the metaphor himself Saturday, describing the southern republics including Macedonia as "unexploded bombs" that if detonated could drag neighboring countries into the conflict. For the moment, the EC is focusing on Croatia, where Croatian independence fighters continue to lose ground to the republic's Serbian minority guerrillas backed by the Serb-dominated Yugoslav federal Army. On Thursday, the peace conference will break into working groups on such issues as borders, possible political and economic ties in a new federation, and the future of the federal Army. The conference is expected to last several months, although Britain's Lord Carrington, the conference chairman, has said intense fighting could make any work impossible. On Saturday at the conference, Croatia's President Franjo Tudjman accused the federal Army of waging a "dirty, undeclared war" inside his republic. Seeking the de facto recognition of Croatia's independence that foreign military intervention would entail, he called for "direct [international] military intervention" to enforce peace. Serbian President Slobodan Milosevic, who is resisting internationalization of the conflict - and who only attended the conference to avoid a cutoff of all EC links - said Croatia's repression of its 600,000 Serb minority was the source of the conflict. He said the Serbs were battling "the repetition of genocide," a reference to the killing of 200,000 Serbs in pro-Nazi Croatia during World War II. Mr. Milosevic claimed that the internal borders of Yugoslavia's republics are simply administrative conveniences, subject to revision. Despite his claim, he signed, along with the EC sponsors and other Yugoslav leaders, a joint declaration stating the conference participants would never recognize "any change unilaterally of internal or external borders." For now, EC leaders seem ready to let the conference accomplish whatever it can. Germany has quieted its renewed threats of last week to recognize Slovenia and Croatia if fighting doesn't cease. At the same time, France appears resigned to the recognition at least of Slovenia, whose independence does not appear to be forcefully protested by Serbia.