Yugoslav Soldier Slain During Croatian Protest : Ethnic unrest: The defense minister says the country is in a state of civil war. He urges federal government to restore order.

Ethnic violence spread to Croatia’s Adriatic Sea coast Monday when more than 30,000 angry protesters stormed the main Yugoslav naval base at Split, killing a federal soldier and commandeering armored vehicles.

Military commanders in Belgrade ordered troops on combat alert and issued a veiled warning to Croatian leaders that they would be held responsible for any further violence against the army.

The deadly clash in Split was the first ethnic confrontation to reach a major city and drew masses of people into the battles that until now have been waged by extremists. It was the latest episode of violence that has claimed 18 lives in less than a week.

Defense Minister Veljko Kadijevic, speaking in Belgrade, said that Yugoslavia is in a state of civil war and urged the federal government to restore order.

Croatian television carried footage of the Split protest, a near-riot, showing demonstrators trying to wrest huge guns from their tank mounts and seizing armored personnel carriers and jeeps from soldiers positioned at the base entrance.

Shots that rang out from the unruly crowd killed a 19-year-old recruit, and at least one other soldier was injured, according to the Tanjug news agency.

Troops used tear gas to disperse the crowd.

The violence prompted an ominous warning to Croatia from the army chief of staff, a hard-line Communist Serb, that the military is ready “to do battle and settle accounts” with those stirring ethnic conflict or provoking the army.

Croatian President Franjo Tudjman is believed to have inspired the Split melee when he suggested a day earlier that thousands rally outside military posts to show support for the Zagreb leadership in the current crisis pitting Serbs against Croats, Yugoslavia’s largest ethnic groups.

Tudjman made the appeal during a visit to the town of Trogir, the federal daily Borba reported in its Monday edition.

When Croatian protesters converged at the naval facility in Split, a renowned tourist resort that is Croatia’s second-largest city, the army demanded that the eight-man federal presidency convene its second emergency session in as many days.

Representatives of Yugoslavia’s six republics and two provinces met in closed session until late Monday, then adjourned until today to ponder a proposal from the federal Defense Ministry, news reports said.

In a statement carried by Tanjug, army Chief of Staff Blagoje Adzic blamed Tudjman for the violence and ordered federal troops to prepare for mobilization.

The protesters rallied in Split to demand that the army dismantle roadblocks erected by Serbs that have prevented food and medicine from reaching Croatian villages in the ethnically mixed and explosive region known as Krajina.

The unruly crowd commandeered armored transport vehicles from soldiers sent in to guard the naval base and were reported to have set off with the hardware toward the town of Kijevo, about 40 miles north of Split.

Federal army units were posted in Kijevo more than a week ago to prevent a possible assault by armed civilians from Knin, a Serbian stronghold to the north that has been the staging ground for a virtual rebellion by ethnic Serbs in Croatia since last summer.

The army barricades were serving to reinforce the roadblocks cutting off Croatian communities from both the coast and the capital of Zagreb.

Serbs and Croats were reportedly erecting new barricades throughout the strife-torn republic, and rail and telephone lines to Split were severed by militants.

Gunfire was heard in eastern Croatia, scene of last week’s deadly clashes, but no new casualties were reported.

Tudjman was to have flown to London for talks with British and European leaders but postponed the visit because of the crisis in his republic. The journey was intended to seek stronger international support and sympathy for Croatia’s independence drive, according to Tudjman’s advisers.

Croatia, a westward-looking republic of nearly 5 million, has joined with neighboring Slovenia in a campaign to dissolve the Yugoslav federation, an alliance formed in 1918 from fractious nations long dominated by the Turkish Ottoman and Austro-Hungarian empires.

But Serbia, the largest of the six republics, vehemently opposes independence for Croatia because of the nearly 600,000 Serbs living there.

Croatian authorities accuse Serbia of instigating unrest in Croatia in hopes of provoking a state of emergency that would allow the Serbian-dominated army to impose martial law and prevent the federation’s breakup.

Many fear increasing outbreaks of violence as the rival republics approach the May 15 date for rotation of the federal leadership. Croatian Stipe Mesic is supposed to take over as Yugoslav president, with nominal command of the army, in just over a week. Mesic will replace Borisav Jovic, a hard-line Communist Serb who has openly sought military intervention to prevent any republic from seceding.

“This is a very dangerous period,” Tudjman’s spokesman, Mario Nobilo, said of the few days remaining until the changeover of the federal leadership. “Not just because the Chetniks (Serbian radicals) are getting more extreme, but because the patience of the Croatian people is at an end.”

Referring to the shooting in Split, Nobilo said he fears that an escalation of the conflict has started because “the Croats are shooting back.”

Most Yugoslavs are hesitant to describe the worsening conflict as the onset of civil war, since only the most extreme nationalists have supported violence. But many describe the recurring outbursts as evidence of an intractable dispute much like those in Lebanon and Northern Ireland.

Special correspondent Michael Montgomery in Belgrade contributed to this report.