Yugoslav Troops Increase Patrols After Another Death : East Europe: Ethnic violence leads to session of collective presidency.

BELGRADE, Yugoslavia —  Federal army troops stepped up patrols in eastern Croatia on Saturday after another person was killed in ethnic violence between Serbs and Croats, raising the three-day death toll to 17.

A large column of tanks and armored vehicles was reported moving toward the town of Vukovar late Saturday after Belgrade television reported that a Serbian man was shot dead by Croatian police at a barricade in the nearby village of Sotin.

Army units in combat gear sealed off the main hot spot of Borovo Selo, a predominantly Serbian enclave just across the Danube from Serbia.

In gun battles Thursday, 13 Croatian police officers and three civilians were killed.

Croatian officials claimed Serbian rebels had decapitated some of the victims.

Federal troops were also reported patrolling streets in Dvor na Uni, another ethnically mixed town where a bomb exploded early Saturday, damaging a Croatian-owned butcher shop. A second bomb exploded in Vukovar. Both towns have been the scene of recurring ethnic clashes for nearly a year.

The army deployments were intensified as the collective presidency was locked in emergency session, attempting to ease the escalating conflict between Yugoslavia’s two largest ethnic groups.

Federal Prime Minister Ante Markovic and acting Defense Minister Blagoja Adzic took part in the crisis session of the presidency, made up of the six republics and two provinces, which commands Yugoslavia’s armed forces and can declare a state of emergency.

After talks that stretched until midnight, the collective leadership issued a vaguely worded statement through the official Tanjug news agency, warning of the risk of civil war from the sporadic violence. The presidency also authorized the federal army to use whatever means necessary to prevent fresh outbreaks of unrest throughout Yugoslavia.

Federal troops and tanks sealed off the most volatile areas after Thursday’s bloodshed, but authorities in some locales have asked that the blockades be eased to allow deliveries of food and other critical supplies.

After the worst day of violence in Yugoslavia since World War II, Serbian militants erected makeshift barricades at the entrance to several villages of the troubled region.

Tensions remained razor sharp in regions of Croatia inhabited by the republic’s 600,000-strong Serbian minority.

Croatia’s nationalist leadership stepped up mobilization of police reservists in eastern portions and in the coastal towns of Zadar and Sibenik, which lie within striking distance of the rebel Serbian stronghold of Knin.

Croatian President Franjo Tudjman ordered the call-up Friday in a televised speech during which he appealed for calm and warned Croats against taking the law into their own hands. Tudjman claimed that “professional insurgents” from Serbia orchestrated Thursday’s attacks.

Serbian officials in Belgrade have denied any hand in the unrest in Croatia, a republic of 4.5 million that has increasingly been at odds with rival Serbia over political, religious and cultural differences.

“We are no longer capable of maintaining law and order,” Vukovar Mayor Stipe Lovrincevic told journalists.

“I think Yugoslavia is already in the initial phase of civil war,” a former U.S. ambassador to Yugoslavia, David Anderson, was quoted as saying by the federal daily newspaper Borba.

The staunchly nationalist Serbian daily Politika said that “it is obvious we are on the brink of chaos.”

Tudjman had been expected to attend the Saturday night presidential session, but instead he sent the republic’s prime minister in a move demonstrating the widespread mistrust afflicting relations among Yugoslavia’s six republics.

Tudjman has repeatedly said his life is threatened by militant Serbs seeking to protect the political arrangement that has afforded them considerable power over the federation of 24 million people.

Serbian authorities, on the other hand, have appealed to the presidency to protect Serbs living in Croatia, who they fear are endangered by Croatian efforts to secede from Yugoslavia and form an independent country.

Meanwhile, 2,000 Serbian nationalists rallied in Belgrade on the 11th anniversary of the death of former Communist leader Marshal Josip Broz Tito, demanding that the remains of the Croat be removed from Serbian soil.

Tito, who ruled Yugoslavia for 35 years, was entombed after his death on May 4, 1980, at a memorial known as the House of Flowers in central Belgrade, which is both the Serbian and federal capital.