BELGRADE — THE European Community (EC) agreement on recognizing the independence of Yugoslav republics has provoked deep concerns that the civil war in Croatia will spread to the powder keg of Muslims, Serbs, and Croats in Bosnia-Herzegovina.Should that happen, the savagery that has convulsed Croatia would almost certainly pale in comparison. Unlike Croatia, the ethnic groups in Bosnia-Herzegovina are densely intermingled, especially in the main towns and cities. "In just 15 days in Bosnia, you might have more casualties than in 15 years in Beirut," said Kamal Kurspahic, who is the editor in chief of Oslobodjenje, the republic's main newspaper. Aware of the danger, Bosnia-Herzegovina's Muslim president, Alija Izetbegovic, has struggled for months to contain tensions fueled by the war in neighboring Croatia and balance the irreconcilable political stands of the three ethnic groups. But this week's EC decision set a deadline of next Monday for requests for recognition of those republics that want it. As a result, Mr. Izetbegovic must decide between demands for independence by the leaders of Bosnia-Herzegovina's 1.7 million Muslims and 800,000 Croats, and calls by the 1.3 million Serbs to remain in a Serb-dominated Yugoslav federation. Izetbegovic must also confront serious opposition to secession by the Serb-dominated federal Army, which has an estimated 80 percent of its lucrative weapons industries located in the republic. Unless he can persuade the EC to postpone its deadline, Izetbegovic will be under enormous pressure to adhere to a decision of the republic assembly and opt for independence, setting the stage for a territorial showdown. "Izetbegovic has no choice but to seek recognition [from the EC], and then the Serbs will immediately announce their separation from Bosnia" and chaos will result, says a Western diplomat. "By asking for an official request, the EC has put new pressure on the situation in Bosnia," said Mr. Kurspahic. "In the case of Bosnia, there is only one problem and that is the most serious: Bosnia is simply indivisible." Izetbegovic appears bound by a memorandum adopted in the 200-seat republic assembly by deputies of his Democratic Action Party, which represents Muslim interests, and the republic's branch of Croatia's ruling Croatian Democratic Union. The memorandum declared the republic "a democratic and sovereign state" and authorized its independence if the six-republic Yugoslav federation established in 1945 disbands. The Oct. 15 vote of the 128 Muslim and Croat deputies was impelled by the same motive that prompted June 25 independence declarations by Croatia and Slovenia - a historic fear of economic and political domination by Serbia, the largest republic. Muslims and Croats "do not want to remain in the rest of Yugoslavia, which they see as a Greater Serbia," Kurspahic said. The assembly vote was boycotted by the 72 deputies of the Serbian Democratic Party (SDP), widely seen as a political puppet of Serbia, which refuses to allow Croatia and Bosnia-Herzegovina to secede with their Serbian communities. To reinforce that stance, the SDP last month organized a referendum in which Bosnia-Herzegovina's Serbs voted to remain in a Yugoslav federation. SDP President Radovan Karadzic appears unwilling to compromise, issuing one of the most vehement denunciations of the EC decision of any Serbian nationalist leader. "The international community, above all the ill-intentioned European Community, has taken over all Yugoslav affairs. The result is encouraging secessionist processes," he said. "Further dictates from the European Community will certainly lead to an escalation of the bloody war." Sitting at the confluence of the legacies of Ottoman and Austro-Hungarian rule, Bosnia-Herzegovina is considered a linchpin of Yugoslavia as well as its most likely ethnic tinderbox. As such, it has long been the target of Serbian and Croatian territorial aspirations. It was a Bosnian Serb who lit the fuse of World War I by assassinating Austrian Archduke Franz Ferdinand in Sarajevo in 1914 in a plan to liberate the republic from Austrian control and merge it with Serbia. The Muslims, descendants of Slavic converts and the largest indigenous Islamic community in Europe, have been caught between the two other ethnic groups. While gravitating toward the Croats, they have been among the strongest supporters of the Yugoslav idea. Izetbegovic advocated a compromise plan that would have converted Yugoslavia into a loose confederation of independent states. They would retain their current frontiers, but allow free transit. The plan lies at the heart of a similar EC proposal, which was embraced as a basis for negotiations by all of the republics except Serbia. After the war erupted in Croatia, Izetbegovic declared his republic neutral, forbade the mobilization of federal Army reservists, and ordered conscripts not to report for duty. Despite his efforts, tensions have risen. Serbs have declared five Serbian autonomous regions in the republic. Croats formed two of their own, one of which comprises seven of the eight communities of one of the Serbian areas. The federal Army has been building up its forces, using undisciplined Serbian reservists who have provoked numerous confrontations with local Croats and Muslims. With the EC decision, Bosnia-Herzegovina appears even more ripe for conflict.