WARSAW, JAN. 19 -- The Yugoslav army reaffirmed today that it is ready to begin enforcing Monday's midnight deadline for the surrender of weapons by "illegal paramilitary forces" throughout the country, an action that political analysts in this ethnically hybrid nation fear could bring on civil war.

The disarmament order and deadline -- originally set for tonight but extended for 48 hours in a terse government statement this evening -- were forced through Yugoslavia's collective presidency 10 days ago by Serbia, the largest of the country's six constituent republics. They were aimed primarily at well-armed police and militia units in separatist Slovenia and Croatia, the most Westernized and prosperous of the republics.

Recently elected non-Communist governments in the two republics are demanding either vastly increased autonomy within a new Yugoslav confederation or outright independence, and nationalist leaders in both insist their police and militia are legal forces and the army has no right to interfere with them. These leaders also have said they fear the army may use the world's preoccupation with the Persian Gulf War as a cover for a crackdown.

A newspaper poll in Slovenia, the most western and second-smallest of the six republics, said this week that 40 percent of the 2 million population believed that, "due to the war chaos in the gulf," an army assault was possible.

"In Slovenia, there is not a single {illegal paramilitary} unit . . . and therefore in Slovenia the return of weapons is not underway," the republic's prime minister, Lojze Peterle, said Friday.

In recent interviews in adjacent Croatia -- the country's second-largest republic after Serbia -- senior officials have said that local police will resist any attempts by the army to disarm them. There are now about 34,000 police officers in Croatia, and the number is growing rapidly. Both Croatia and Slovenia have made large-scale purchases of handguns and automatic weapons for local police over the past six months.

The crisis in Yugoslavia echoes that in the Soviet Union, where the Kremlin has used army troops to crack down on separatist governments in Lithuania and other restive Soviet republics. As in the Soviet army, many senior military officers in Yugoslavia are doctrinaire Communists and adamantly oppose the breakup of the current federation.

The Yugoslav situation is also complicated by ethnic hatreds. The army officer corps is dominated by Serbs, the country's largest ethnic group and -- spurred by the demogogic nationalism of Serbian President Slobodan Milosovic -- one that seems committed to keeping Yugoslavia together. Tens of thousands of Serbs were victims of a fascist Croatian government during World War II, and growing nationalist rivalries between Croats and Serbs have rekindled Serbian fear and resentment.

The order to disarm also has been resisted in Kosovo, a troubled province of Serbia where 90 percent of the 1.5 million residents are ethnic Albanians. Serbian police, responding to what they say is a local insurrectionist campaign to link the province to neighboring Albania, have imposed the equivalent of martial law throughout Kosovo and have been accused of committing flagrant human-rights violations.

"{This} decree can only provoke tragic consequences, and that is why we are rejecting it," Zekerija Cana, an ethnic Albanian leader in the province, said Friday.

One of the few groups to honor the government order to disarm has been the ethnic Serbs living in Croatia. Hundreds of Serbs in the republic had armed themselves with weapons stolen from police armories last year, claiming they needed the guns to protect themselves from local police. Croatian police, fearing army interference, had not attempted to take the weapons back.