BELGRADE -- The electoral triumph of Serbia's nationalistic President Slobodan Milosevic seems likely to accelerate Yugoslavia's fitful moves toward dissolution, Western diplomats fear.

The people of Serbia, the largest of the six republics that make up Yugoslavia, voted last Sunday for the 49-year-old former Communist leader, who combines hard-nosed concern for Serbian interests with an appetite for centralized power.

Most importantly, Milosevic repeatedly has refused to talk with the newly elected leaders of the northern republics of Croatia and Slovenia, who have proposed looser ties among the republics as an alternative to secession. His refusal to talk has persisted in spite of pleas from major Western governments.

A portent of the hard line that Milosevic can be expected to take on negotiations about Yugoslavia's future is the enactment this week of an amendment to the Serbian criminal code that makes it a crime punishable by imprisonment for individuals to criticize the Serbian state or its leaders.

Pressure for a breakup of Yugoslavia has been building throughout the year as voters in the republics have elected leaders with ambitious nationalist agendas. The potentially ominous impact of the Milosevic victory can only be understood in relation to those agendas.

Slovenes will vote Dec. 23 in a referendum on independence. Slovenia's militia has been ordered to guard public buildings against a possible takeover by the Yugoslav army.

The legislature of Croatia, the second largest republic and a historic adversary of Serbia, is preparing a new constitution that will give nationalist President Franjo Tudjman complete control over the republic's military, as well as power to dissolve the government.

In the Serbian province of Kosovo, which is under occupation by Serbian police and administrators, the ethnic Albanian majority -- 90 percent of the population -- boycotted Sunday's election. But young people there are frustrated with nonviolent protests and leaders fear they soon will not be able to control anti-Serbian violence.

Western diplomats say the federal government has never been weaker. The free-market economic reforms of Prime Minister Ante Markovic are unraveling. Milosevic's Serbian government has attacked the federal reform package, which is similar to programs underway in several East European countries, as a scheme to impoverish the Serbian people.

Most ominously, the federal army has threatened that it would use force to prevent a breakup of the country. The well-armed 180,000-man force is led by an officer corps that is strongly pro-Communist and dominated by Serbs.

The defense minister, a Serbian general, said last week that the army will disarm police and militia in the republics. Croatia and Slovenia have demanded the general's resignation. Prime Minister Markovic, in a telling display of the impotence of his office and the power of the army, has refused comment on the matter.

The dovetailing of these events has led senior diplomats in neighboring Italy and Austria to acknowledge the increasing likelihood of a north-south division in Yugoslavia. Diplomats from those two countries have said that their governments foresee the creation of an independent Slovenia on their borders.

Croatia presents a far more volatile problem. More than half a million ethnic Serbs live inside that republic. With the unofficial encouragement of Milosevic's government, Serbs in southeastern Croatia have demanded an "autonomous state" and have put up sporadic armed resistance to Croatian police.

Amid the blurring pace of democratic change across Eastern Europe in the past two years, Milosevic is an old-style authoritarian who appears uncomfortable in any situation he cannot dominate.

In the campaign for Serbia's first multi-party election since World War I, Milosevic refused to debate any of his opponents. He also refused to appear on television in slots reserved for candidates.

Instead, he campaigned in the "news" as presented by the Serbian media that he controls. A well-placed government source said Milosevic meets on an almost daily basis to discuss news coverage with the editors in chief of Serbia's television and of the main daily newspaper, Politika.

Milosevic survives as a hard-liner -- indeed his 65 percent presidential victory shows he is thriving -- by constantly reassuring Serbs that he is standing up for their interests.

Under the dictatorship of the late Marshal Tito, a Croat who died in 1980, nationalist ambitions in Yugoslavia were muffled by the Communist Party. Serbs felt, with some justification, that they were singled out for harsh treatment. Tito gave considerable autonomy to two provinces carved out of Serbia.

Milosevic gutted the autonomy enjoyed by provincial authorities in Kosovo and Voivodina. In so doing, he won folk hero status among many Serbs.

While he has managed to win the support of most Serbs, Milosevic and his Socialist (formerly Communist) Party have demonstrated a marked inability to manage the Serbian economy.

In recent years, and especially during the election campaign, a number of unprofitable state industries have met their payrolls only after Serbian banks were ordered by the Milosevic government to make "contaminated loans," according to Yugoslav economists.

Serbian banking officials have insisted that such loans must stop. If they do, Milosevic may soon have to deal with strikes and large-scale social unrest among workers whom bankrupt industries can no longer afford to pay. It is estimated that one in three Serbian enterprises losses money.

In bucking a trend that has seen the defeat of former Communists in four other Yugoslav republics, as well as across much of Eastern Europe, Milosevic may find that the cost of political victory is isolation.

Some say that much depends on how the opposition fares in the second round of voting for the 250-seat Serbian parliament.

After winning just nine seats in the first round, however, it appears that the best the opposition can hope for is to transform the legislature from a rubber stamp into a voluble forum for dissent.

Under the new Serbian constitution, however, Milosevic can impose a state of emergency and dissolve the government whenever he decides there is a need.