Slovenia Yields in Part to Belgrade Ultimatum : Yugoslavia: A cease-fire seems to be holding. The European Community freezes arms sales and halts aid.

The breakaway republic of Slovenia released prisoners of war and withdrew defense forces from Yugoslav federal army garrisons on Friday, but its refusal to give up symbolic moves toward independence drew sharp criticism from the army and threats of another attack.

While Slovenia’s compliance with an ultimatum from the federal presidency in Belgrade was selective, a cease-fire agreement appeared to hold for the second day, easing tensions in the alpine republic and lessening European fears of a full-scale war.

Diplomatic efforts continued toward resolving the crisis that has killed dozens and plunged Yugoslavia into chaos.

The European Community planned to send a delegation to Yugoslavia today to make preparations for a truce-monitoring team, and EC ministers meeting in the Netherlands froze arms sales and suspended almost $1 billion in aid in hopes of forcing the combatants to find a peaceful solution to what seem to be irreconcilable differences.

Meanwhile, ethnic violence intensified in neighboring Croatia, which along with Slovenia declared independence from Yugoslavia last month. Armed Serbian rebels in Croatia exchanged gunfire with federal troops and with Croatian police and torched several homes in the northern town of Mirkovci.

A Croatian policeman manning a roadblock a few miles to the south said there had been casualties, but he had no details of the continuing battle.

Croatian radio said national guard units had been deployed to clear “Serbian terrorists” from Mirkovci.

At least 43 people have been killed in ethnic violence in Croatia in the last two months, and the deployment earlier this week of a massive federal army force to ethnically mixed regions of the republic has heightened concern that the conflicts will escalate.

The Croatian leadership in Zagreb has demanded withdrawal of both the Serbian radicals and the army units whose mission in the volatile region has not yet been made clear.

Further disturbing signs emerged Friday that the federal army is fractured and out of the political leadership’s control.

A statement issued by a senior army officer, Lt. Gen. Marko Negovanovic, accused Yugoslav Prime Minister Ante Markovic of shirking his duties in failing to support army actions taken to prevent Slovenia’s secession.

Markovic responded to the June 25 declarations of independence by Slovenia and Croatia by ordering the army to protect the borders of Yugoslavia, including those of the rebellious republics.

Fierce fighting erupted at Slovenia’s border crossings into Italy, Austria and Hungary, as control of the customs checkpoints has become a symbolic measure of who is in charge.

The 180,000-strong Yugoslav People’s Army also unleashed an aerial blitz on Ljubljana, the Slovenian capital, and other strategic targets, inflicting civilian casualties and igniting a determined resistance among the usually docile Slovenes.

Three cease-fire accords were announced over the past week, but only the latest--negotiated by the local army command and Slovenian officials--has brought about relative calm in the republic, still mobilized to repel an invasion.

On Thursday, Markovic told reporters in Belgrade that he never authorized the use of armed force and that no federal sanction had been given to the army’s massive deployment a day earlier of tanks and armored units from Serbia into neighboring republics.

The criticism by Negovanovic, the federal general, further undermined the government’s authority, which was already minimal in view of its admitted inability to control the army.

An armored column of 180 vehicles took positions on the Serbian border and in Serbian-dominated regions of Croatia and Bosnia-Herzegovina earlier this week, raising suspicion that the army was marking out the borders of a “Greater Serbia” sought by the biggest republic’s nationalist leaders.

Slovenes intent on building their own statehood have pointed to the renegade army behavior as evidence that federal authority in Belgrade has collapsed. They claim that their republic is better off providing its own administration and defense against threatened attacks.

The hard-line Communist chief of staff of the armed forces, Gen. Blagoje Adzic, vowed Tuesday to crush Slovenian independence with “a massive and rigorous military strike.”

In Gen. Negovanovic’s statement, the army claimed that Slovenia was still blocking some of its barracks and that shots were fired at garrisons overnight.

Slovenian officials say the gunfire came from inside the federal army compounds.

“There is no doubt that Slovenia is not respecting the cease-fire and the decisions of the federal presidency,” Negovanovic said in Belgrade.

He also accused Slovenia of beefing up forces around Maribor, the republic’s second-largest city.

Jelko Kacin, information minister for Slovenia, said the territorial defenses were being scaled back. He said that 10,000 reservists had been deactivated, from about 40,000 deployed earlier, but that an alert would continue as long as there was the threat of another army attack.

Many of the vehicle barricades erected around the Slovenian capital on June 27, when a punishing federal assault spurred a massive defense drive, were dismantled early Friday.

But in clear defiance of a Yugoslav presidential order to free up all roads through Slovenia, territorial defense units erected tank traps and dumped loads of gravel and sand across major roadways at hundreds of junctions to prevent any advance of federal armor.

The Yugoslav presidency, which is supposed to command the armed forces, was restored last Sunday after a six-week paralysis with the election of Croatia’s Stipe Mesic as head of state. But since Serbia effectively controls four of the eight presidential delegates, and Slovenia’s representative has refused to take part, Mesic and the two other members are automatically outvoted.

The eight-point presidential order issued late Thursday smacked of Serbian interest and army influence. While demanding that Slovenia withdraw its defense forces, it made no mention of the huge army deployment or republic police actions such as Serbia’s suppression of ethnic Albanians in its province of Kosovo.

“They are expecting miracles,” Kacin, the Slovenian information minister, said in responding to the presidential order.

Some of the measures were complied with, such as release of the 2,300 federal prisoners who surrendered or were captured by the territorial defenders during clashes with the army earlier this week.

The International Red Cross confirmed that Slovenian officials had allowed prisoners to board buses and trains for their home republics. Ljubljana also said it was returning captured tanks and other armaments to the federal bases.

But an accompanying presidential directive to hand over border controls to the Belgrade government has been openly defied.

Slovenia considers security and customs to be a matter for republic forces and has vowed to defend the crossings from any federal attack.

A Sunday night deadline looms for turning over the border crossings, but the presidential statement did not make clear the consequences of defiance.

Many in Slovenia fear that another federal assault is brewing, although the army’s firepower now seems trained on regions of Croatia and Bosnia where ethnic Serbs make up a majority of the communities.

Besides suspending its $900 million in annual aid to Yugoslavia, European Community officials said they would be sending three truce monitors to Yugoslavia today. The officials are from the Netherlands, Luxembourg and Portugal--the countries that are the present, past and next holders of the EC presidency.

The EC officials, meeting in the Hague, also appealed to other nations not to send arms either to the federal government or to the two breakaway republics.

Dutch Foreign Minister Hans van den Broek said Friday that the EC hopes to expand the truce-monitoring group by seeking to enlist members from several nations of the Conference on Security and Cooperation in Europe, which includes all European countries plus the United States and Canada.

Times staff writer William Tuohy in London contributed to this report.

The Toll in Slovenia

List of casualties in Slovenia released Friday by Slovenian Red Cross.

KILLED INJURED CAPTURED Federal army 36 160 2,316 Territorial defense forces 3 66 not given Federal police 2 22 129 Civilians 5 38 2 Foreigners 10 2 not given TOTAL 56 288 2,447