Thousands Flee as Serbs Seize Bosnian ‘Safe Area’ : Balkans: NATO halts air strikes after rebels threaten to kill Dutch peacekeepers. Defeat is devastating blow to U.N.

Bosnian Serb forces, ignoring NATO air strikes, captured the U.N.-designated “safe area” of Srebrenica on Tuesday, sending thousands of terrified Muslim refugees into an exodus and handing the United Nations a devastating defeat.

A Dutch U.N. peacekeeping battalion deployed to defend the eastern enclave also withdrew ahead of the invading Bosnian Serbs. Warplanes from the North Atlantic Treaty Organization were called off after the rebel Serbs threatened to kill 30 Dutch peacekeepers in their custody, Dutch officials said.

“Srebrenica has fallen to the Bosnian Serb army,” U.N. spokesman Alexander Ivanko said. “The town is effectively under Bosnian Serb control.”

The loss of the Srebrenica enclave, one of six established by the United Nations in 1993 to protect civilians from ethnic warfare, represents a disastrous humiliation for the world body, whose mission here appears doomed. It is the first government-held enclave to fall into Serbian hands, but others are now threatened.

Along with delivery of humanitarian aid, protection of the “safe areas” was the principal duty of the U.N. peacekeeping force in Bosnia-Herzegovina.

For days, U.N. officials had insisted that the Bosnian Serb offensive around Srebrenica was a limited operation, even as the nationalist Serbs massed troops, shelled the town, attacked U.N. observation posts and captured U.N. peacekeepers.

The failure of the United Nations to defend the enclave also delivers another victory to the Bosnian Serbs, who have used the war to seize 70% of Bosnian territory and whose attacks on civilians and disregard for human rights have earned many of their leaders scrutiny by an international war crimes tribunal.

Bosnian Serb television claimed that nationalist Serb forces would take a second U.N.-protected enclave, Zepa, in a matter of hours. Bosnian government radio reported Bosnian Serb troops massing on two sides of Zepa, an isolated “safe area” harboring 16,000 Muslim refugees.

With the fall of each enclave, the chances for Bosnia’s survival diminish.

Angry, anguished Bosnian government officials blasted the United Nations on Tuesday for failing to act sooner to stop the Bosnian Serb onslaught, and they renewed demands that the United Nations redefine its mission or get out.

“The NATO [response] was too little, too late,” said Prime Minister Haris Silajdzic, who had been in radio contact with Srebrenica. “The people of Srebrenica have been sentenced to death. . . . The betrayal is complete.”

Making a last-stand defense of Srebrenica, Dutch troops called for NATO close-air support Tuesday after two U.N. observation posts, a U.N. base compound and a hospital came under Bosnian Serb attack. The United Nations on Sunday had threatened to use air power if the Serbs renewed attacks on U.N. positions.

NATO scrambled Dutch F-16 fighters and U.S. A-10 tank killers, as well as U.S. radar-jamming Wild Weasels, to do the job. At least one Bosnian Serb tank was hit, U.N. officials said.

A spokesman for Dutch Defense Minister Joris Voorhoeve said he asked the United Nations to call off a third air strike after Bosnian Serb forces threatened to kill the 30 Dutch peacekeepers seized earlier in the campaign to take Srebrenica.

Ninety minutes after the first air strike, Bosnian Serbs shelled the U.N. headquarters in Sarajevo, which sits adjacent to the U.S. Embassy. No one was hurt, but sporadic shelling continued through the night and early today.

NATO warplanes continued to fly overhead even as Srebrenica was being overrun by rebel Serb troops.

About 1,500 Bosnian Serb troops backed by tanks and heavy artillery wormed their way around a thin line of about 70 elite Dutch peacekeepers positioned along the southern perimeter of Srebrenica, then marched on to the town. “They [the Dutch] were slightly overmatched,” U.N. military spokesman Lt. Col. Gary Coward said.

As the Bosnian Serbs advanced, the entire Dutch battalion retreated to its base compound at Potocari. The air strikes had failed to stop the Bosnian Serbs.

“It showed the limitation of air power when [it is] not helped by ground maneuvers,” Ivanko said. “And what kind of ground maneuvers can you have when all you have is 450 lightly armed peacekeepers being attacked by a big, strong European army?”

The Bosnian government army reported that nationalist Serbs occupied several houses in Srebrenica and were sniping at the few civilians left in the town.

Overrun by the Bosnian Serbs, Srebrenica cleared out in a chaotic rush. Thousands of panicked, desperate Muslim refugees--most of whom had already been uprooted from their homes by Bosnian Serb gunmen at the start of the war--fled on foot to Potocari, about three miles north of Srebrenica.

Between 20,000 and 30,000 refugees were crowded around the compound late Tuesday, seeking shelter in barns, an abandoned factory and open fields. There was no food, no water, no relief.

“What we are seeing now is the most unfortunate scenario--[the] massive, uncontrolled exodus of people of Srebrenica,” said Kris Janowski, spokesman for the Office of the U.N. High Commissioner for Refugees. “They are not hostile. They are just desperate people fleeing.”

The rebel Serbs apparently met with little resistance as they took over Srebrenica. Some skirmishes were reported as the Bosnian government army tried but was not able to defend the enclave, U.N. officials said.

When Srebrenica was established as a “safe area” two years ago, government forces agreed to surrender their heavy weapons to the United Nations in exchange for a pledge of U.N. protection.

Still, the army retained some light weapons, making the programmed demilitarization incomplete. The Bosnian Serbs are citing that as justification for their attack on Srebrenica.

“This action is aimed [at] neutralizing the terrorists,” Bosnian Serb commander Gen. Ratko Mladic said Tuesday in a letter to British Lt. Gen. Rupert Smith, the commander of U.N. forces in Bosnia. “Our activities are not aimed against civilians.”

Mladic said that 100 civilians have been killed and 200 wounded by government commando raids in recent months. The United Nations has confirmed that small-scale raids have occurred but has not confirmed casualties.

The Bosnian Serbs have grown increasingly defiant of the West and have skillfully exposed the flaws in a weak, splintered U.N. mission. After NATO launched punitive air strikes against them on May 25-26, the Bosnian Serbs took more than 370 U.N. peacekeepers hostage and released them only on the rebels’ terms.

The ease with which the Bosnian Serbs occupied Srebrenica--and the likelihood that the world powers will let them get away with it--will only reward their intransigence and defiance, analysts here said.

“I can sum it up in one word: The Serbs are implacable,” said a Western diplomat. “They push and push on the rotten door until it caves in. I can only think this will not be the end of their demands and the other enclaves are in danger. Now that the Serbs have smelled weakness, they’ll keep pushing.”

Times staff writer Stanley Meisler in Washington contributed to this report.