Battle Rages Over Serb Supply Route : Balkans: Fight over key transport corridor could merge scattered conflicts into wider war.

The explosions that thunder just beyond the muddy cabbage fields here signal another day in a ferocious battle for control of a vital supply corridor that is the lifeline for warring rebel Serbs.

Crossing the Sava River by ferry to reach his Orasje home, Marijan Pejic winced as a multiple-rocket launcher punched the air.

“Three kilometers,” he assessed the distance, then shrugged away any concern. “Our soldiers will keep the Serbs away.”

For almost two weeks, Bosnian Serbs have been pounding this town of 5,000 and its environs with heavy artillery, tank fire and rockets. Bosnian Croats who control the area have responded in kind. Hundreds of shells an hour were recorded in the heaviest exchanges. Dozens of people have been killed or wounded, including civilians, according to the armies of both sides.

The fighting here, however, has been largely overshadowed by renewed warfare in Sarajevo, the deadly shelling of Zagreb and Croatia’s recapture of occupied territory. Yet the battle along this corridor has the potential, more than anywhere else, of merging the many Balkan conflicts into a single, catastrophic war.

At stake is the only Serbian supply route that links Serbia, in the east, with land the rebels have seized farther west and south in Bosnia and Croatia in their campaign to build a “Greater Serbia.”

The corridor, which runs along northern Bosnia and skirts the Sava River, is used to transport all matter of weaponry, gasoline and other equipment to rebel positions, United Nations military analysts say.

This vital supply line took on added strategic value for the Serbs this month when Croatia recaptured territory that had been held by Serbs, including part of a major cross-country highway to Belgrade.

Losing control of that highway meant the Serbs in Croatia and in much of Bosnia must now rely almost exclusively on the corridor route, analysts say. Cutting the corridor could be the single most damaging blow to the Serbs, and many observers predict that it would force Serb-led Yugoslavia to act directly against Croatia and Bosnia.

It is in the area of Orasje, a Croat-controlled bridgehead that dips below the Sava River, that the corridor is the most narrow--and, in the view of the Serbs, most vulnerable. In the Serb-held city of Brcko, 15 miles southeast of Orasje, the corridor is only about 2.5 miles wide, U.N. and Croatian military sources say. It could be squeezed from the north by the Bosnian Croats, who are believed to receive ample support from the army of Croatia proper, and from the south by the army of the Muslim-led Bosnian government.

The Bosnian Croat militia defending the Orasje pocket insists that it is not trying to cut the corridor--for now.

“Right now our orders are to defend our territory, only,” Capt. Mirko Zivkovic said in an interview in his office. “But, of course, if there is no peaceful solution, we will get different orders.”

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The Bosnian Serbs, already smarting from gains by newly aggressive Croat and Bosnian Muslim armies, apparently decided not to take any chances and launched the current offensive May 5, using up to 18 tanks, infantry and formidable firepower, according to U.N. officials.

Besides staving off a Croatian offensive, the Serbs’ goal appears to be to widen and better secure the corridor by overrunning the Orasje pocket and pushing the Bosnian Croat line north to the Sava River.

The Croats also believe that the Serbs are exacting revenge for Croatia’s recovery earlier this month of the part of territory known as Western Slavonia, which the Serbs had occupied in the 1991 Croat-Serb war and held until now.

It was the biggest loss of territory suffered by the Serbs since the wars of the former Yugoslav federation began four years ago.

“They wish to accomplish at least something in one battlefield to be able to boost the morale of their troops and people,” Zivkovic said.

In Orasje on Wednesday, the shelling was especially intense. The militia at first barred reporters from entering the city, then assigned them to a military guide and restricted their movements.

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The Orasje pocket is part of a self-declared Bosnian Croat “republic” called Herzeg-Bosna and backed by Zagreb. It is not recognized internationally.

But the Croats there, who are among some of the most staunchly nationalistic, like to fly flags with their own national emblem and regard their militia as an independent army.

In fact, the militia denies that it receives help from the Croatian army, despite what U.N. peacekeepers cite as substantial evidence to the contrary.

During the visit Wednesday, drivers of huge transport trucks were seen switching their license plates between those of the Croat army and those of the Bosnian Croat militia.

If the militias of the Bosnian Croats and Bosnian Serbs can be seen as proxy armies for Zagreb and Belgrade, respectively, then the specter of a larger war is more clear.

Some analysts and diplomats regard the cutting of the corridor as such a damaging provocation that the powerful Yugoslav army would feel compelled to enter the fray.

If, however, reports prove true that Serbian President Slobodan Milosevic, whose nationalistic fervor inspired Serbian separatists, is close to recognizing Bosnia’s borders, then the likelihood of a wider war may diminish.

Milosevic has been under pressure for some time from the United States and Europe to accept Bosnia’s legitimacy in exchange for the lifting of economic sanctions against Yugoslavia. He has, thus far, refused.

The shell-shocked people of Orasje, meanwhile, gird for war.

Mato Zlatarevic, a cook until he was drafted into the militia, sat in his home, its shattered windows papered over, and recalled the pre-dawn explosions last week that nearly killed his neighbors, Anna and Djuro Zlatarevic, who are not related.

The wall of Anna and Djuro’s house was peeled away, the barn destroyed and two pigs killed. Djuro’s body was pierced with hundreds of shards of glass that were hurled through the air. A crater, about 20 feet wide and eight feet deep, sits in the field behind the house, the product, says the military, of a powerful ground-to-ground missile fired from Serbian positions.

“We live in total fear now,” Mato Zlatarevic said. “I’ve been here since before the war began, through all the air raids, and I was never afraid. But now I am afraid.”