Yugoslav President Borisav Jovic resigned Friday to protest a refusal by a majority of the eight-man federal presidency to authorize army intervention in the nation's political crisis, and the communist military high command indicated it was preparing to act on its own.

Vice President Stipe Mesic, a Croatian nationalist known to be disliked by the military's Serbian-dominated leadership, announced that he would assume the powers of the rotating chairmanship of the collective head of state, which he is due to take for a year on May 15.But he admitted that the line of succession was unclear as there is no provision in the Yugoslav Constitution covering the federal president's resignation.

Mesic summoned an emergency presidency meeting for midnight Friday, but it was later canceled, according to state-run Croatian radio.

Jovic's stunning televised resignation came shortly after the presidency, meeting for the third time this week in its capacity of supreme armed forces commander, rejected again a demand for "emergency measures" by the army. The first meeting was held Tuesday, three days after Belgrade was rocked by clashes between police and anti-communist protesters that left two people dead.

Croatian officials said five members of the collective presidency, composed of representatives of the six republics and two provinces, voted against the military. Jovic, along with the representatives of Serbia's Vojvodina Province and Marxist-ruled pro-Serbia Montene

gro, supported the army.

Jovic, a 63-year-old economist regarded as a close ally of the army's communist high command, said he was relinquishing the presidency's rotating chairmanship exactly two months before he was to have turned it over to Mesic.

A statement from the office of the presidency said Jovic submitted his resignation for acceptance to the assembly of Serbia, which was next scheduled to meet March 20. Presidency members are appointed by republic legislatures.

In a speech that added to uncertainty over the future of the multi-ethnic nation of 23 million people, Jovic accused his presidency colleagues of a "lack of trust in the armed forces of the country" to end months of dangerous political and ethnic tensions that have led it to the verge of civil war.

But Bosnia-Hercegovina Republic President Alia Izetbegovic, a Muslim, accused Jovic of supporting army intervention to help preserve the privileges and position that the military leadership, the nation's last bastion of conservative Marxism, will lose under Western-style political and economic reforms.

A military statement said, "The staff of the Supreme Command of the Army Forces of the Socialist Federal Republic of Yugoslavia is assessing the current situation in connection with the rejection of the proposal and measures, in connection with this, it will undertake."

It said it wanted to "guarantee the prevention of interethnic armed conflicts and a civil war" in the nation of six main ethnic groups who practice three major religions, speak more than one dozen languages and use two different alphabets.

The military command has repeatedly threatened to intervene in the crisis rooted in a festering dispute over the future of the country, which Croatia and Slovenia want dissolved into independent states. Serbia's communist regime shares with military chiefs a desire to maintain the socialist-based federation with its 8.5 million-strong mostly Christian Orthodox Serbian majority.

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Don't go

The U.S. State Department is urging Americans to defer non-essential travel to Yugoslavia because of heightened political tensions, ethnic demonstrations and other dis-ruptions.