Voters in Slovenia endorsed an independent state in a plebiscite, authorizing the republic's nationalist government to secede from the Yugoslav federation, officials said.

But despite Sunday's vote, leaders of Yugoslavia's most westernized and economically developed republic said they did not plan to immediately leave the increasingly precarious multi-ethnic federation.Slovenia, along with neighboring Croatia, wants the country of 23 million founded in 1918 transformed into a confederation of independent states linked by a common market. Their stand is rooted in fears of economic and political subservience to Serbia, the nation's largest republic, whose communist leaders have been fanning Serbian nationalism.

With 55 percent of the votes counted in the plebiscite in Slovenia, 94 percent of voters endorsed independence, 5 percent voted no and 1 percent of the ballots were invalid, election commission officials said late Sunday.

About 4,200 polling stations closed Sunday after 12 hours of voting during which 1,279,870 people, or 88.2 percent of nearly 1.5 eligible voters, cast ballots, the officials said.

The only sentence on the ballot, to which voters had to respond with "yes" or "no," read, "Are you in favor of an autonomous and independent Slovenia?"

Slovenian Prime Minister Lojze Peterle said, "Now, we have to make new steps to build Slovenia's independence and statehood. But the path which is in front of us will not be an easy one."

In balloting elsewhere, an alliance of the major Serbian opposition groups claimed an early lead in returns from the final round of the first post-war multi-party assembly elections, saying it trounced the ruling communists in Belgrade and several other towns.

Howver, opposition officials declined to forecast whether they would achieve their longshot goal of denying a majority in the 250-seat Serbian Assembly to President Slobodan Milosevic's Socialist Party of Serbia, the name adopted by the communists in July.

At stake in the runoffs were 154 seats for which no candidates won more than 50 percent of the ballots cast in the first round Dec. 9.

In Serbia's neighboring republic of Montenegro, voters also cast ballots in the second round of that republic's presidential election. Results wre not expected until Monday.

In Slovenia, the ruling Democratic Union - a coalition of nationalist parties that ousted communists in April - has said it would not declare independence immediately but would use the plebiscite as a bargaining chip in a dispute over the future constitutional framework of Yugoslavia.

The Croatian Assembly adopted a constitution Friday containing a secession process, prompting the republic's largest enclave of minority Serbs to declare itself the autonomous province of "Krajina."

Slovenia also objects to providing financial support to Serbia, which has resisted economic reforms despite widespread fears it is close to bankruptcy.

"I am not against Yugoslavia, but because of the domination of the leadership of Serbia, Slovenes feel that they will not have a good future," Lorena Dobrila, 24, a student, said after voting in the capital of Ljubljana, 350 miles northwest of Belgrade.

Slovenian Defense Minister Janez Jansa said the decree authorizing the plebiscite forsees a "six-month transition period" in which the government will seek talks with other republics on the constitutional crisis while preparing "all laws needed to begin functioning as an independent state."

Milosevic, re-elected Dec. 9, has so far refused to negotiate, saying he will only accept confederation if Serbia's present borders are expanded to include Serbian enclaves in other republics.