The drive for peace in Bosnia was threatened Friday by fighting that raged in the northwest, where government and Croat troops advanced toward this panic-stricken Serb stronghold.
The Serbs of Banja Luka, a heavily fortified town considered invincible for most of the 3 1/2-year-old war, began packing their suitcases Friday in case they had to flee. Checkpoints were set up around the city to stop them from taking the narrow Serb-held corridor to Serbia.
Bosnian Serb leaders threatened to pull out of peace talks and demanded NATO airstrikes to halt what they called an offensive by Croat and Muslim-led government troops. The fighting is in violation of a 60-day truce that mostly silenced guns elsewhere in Bosnia for the second day.
The United Nations confirmed fighting across the northwest, scene of some of the worst Serb atrocities and most tenacious battles of the war. But they did not know who was attacking whom.
"There has not been a cease-fire, but purely a continuation of hostilities," said Lt. Col. Chris Vernon, a U.N. spokesman in Sarajevo.
By capturing Banja Luka, the government and its Croat allies would greatly strengthen their bargaining position in peace talks, where territorial limits and a power-sharing arrangement are to be negotiated.
Serbs, who have been promised a separate political entity, could lose their claim to a broad section of northwest Bosnia they have held for almost the entire war. Winning more territory would give the government and Croats an argument for more power in a joint postwar government.
Sanski Most, Prijedor and the surrounding region were also the sites of some of the most infamous Serb prison camps early in the war. It may prove difficult to restrain Muslims and Croats bent on avenging Serb atrocities.
At least two villages about 12 miles south of Banja Luka were evacuated, and one was on fire, said Banja Luka's mayor, Predrag Radic.
Reporters were not allowed to travel to the area, but the sound of distant artillery fire from the west rumbled all afternoon through the streets of Banja Luka. U.S. Air Force Capt. Scott O'Grady was shot down by a Serb missile on June 2 near the town, the biggest in Bosnian Serbs' hands.
Ambulances screamed through the streets bringing wounded from the front to Banja Luka's military hospital, where the smell of blood filled the corridors. All seven operating rooms were in constant use. Nurse Suzana Vrhovec said from 50 to 60 wounded were treated each day last week.
About 30 miles to the northwest, Prijedor was shelled during a visit by rebel Serb leader Radovan Karadzic, local reporters said. The town lost electricity and its radio went off the air. Bosnian Serb army sources said government troops were within 12 miles.
"The whole world is celebrating peace, but we don't have peace," Karadzic said. "America has brokered this cease-fire, and it is obliged to stop the Muslims."
Deputy Serb commander Gen. Milan Gvero and political leader Nikola Koljevic also indirectly called for airstrikes by the North Atlantic Treaty Organization against the Muslims and Croats.
Gvero said his enemies should be "punished with all means available." That includes airstrikes, which so far have only been used against the Serbs.
Koljevic also called on the international community to "do everything to stop" the government and Croat forces, and threatened to pull out of the peace process.
"If the U.N. and international community don't do everything to stop the Muslims and Croats . . . we will consider very seriously stepping out of the peace process and asking Yugoslavia to do the same," Koljevic told Associated Press Television. Yugoslavia is negotiating for the Bosnian Serbs.
Directly west of Banja Luka, U.N. troops were allowed into Sanski Most for the first time since government and Croat troops seized the town last week.
U.N. spokesman Vernon said the peacekeepers had Bosnian government escorts and could not see much during the few hours they were allowed to stay.
The Serbs are fuming that the government delayed last week's cease-fire by two days to take Sanski Most.
Statements from Serb leaders have indicated panic, and they have appealed for help from neighboring Serb-led Yugoslavia.
As many as 50,000 Serbs have been forced to flee ahead of the latest government-Croat attacks.
The U.N. refugee agency said it might have to airlift food to Banja Luka to cope with the influx.
But the Serbs have continued expulsions of Muslims and Croats from their territory in the northwest in recent days, U.N. refugee officials say.
Expulsions were said to have tapered off Friday, but aid workers were alarmed by fresh reports from arriving refugees about violence and men being bused off to unknown locations.
U.S. negotiator Richard Holbrooke hoped to use the current truce to start peace talks this month that would set the stage for an international peace conference in Paris to settle the conflicts in former Yugoslavia.
A NATO-led multinational force of some 100,000 troops--including up to 25,000 Americans--would then be sent to Bosnia to police the settlement.
As congressional fears about U.S. troops on the ground mounted, U.S. Defense Secretary William J. Perry said they would be deployed for a year at most.
Bosnia's war started in April, 1992, when armed Serbs rebelled after a Muslim-Croat vote to secede from Serb-led Yugoslavia. About 200,000 people are believed dead or missing.