28,000 Bosnians Face Expulsion, U.N. Says : Balkans: Refugee officials hope to forestall Serbian plan and avoid becoming accomplices in resettlement.

United Nations officials warned Tuesday that Serbian forces are trying to expel about 28,000 Bosnians, most of them Muslims, from their homes around the Bihac area in northwestern Bosnia-Herzegovina.

Calling it one of the largest single acts of “ethnic cleansing” since the war in Bosnia began in May, the Office of the U.N. High Commissioner for Refugees hopes to forestall the expulsion and to avoid becoming a pawn in the Serbian plan to remove Muslims from the area.

Lars Nielsen, field coordinator for the high commissioner’s office, said that he, officials of the U.N. peacekeeping force and local Serbian and Muslim leaders plan to meet in the Bihac area today to discuss the potential exodus.

He said the Muslims are from four towns in the Bosanska Krajina region of northwestern Bosnia, an area with a Muslim population of more than 80%.

The city of Bihac, with a population of 70,000, has been subjected to artillery attacks daily since mid-June, and city officials have been locked in an intense debate for weeks over whether to evacuate women and children from the town. So far, there has been no evacuation. The town’s most influential Muslim leaders fear it would mark the first step in surrendering their homes to the Serbian militiamen who surround the city.

Two weeks ago, U.N. refugee officials complained bitterly of being forced into helping in the evacuation of more than 7,000 residents of Bosanski Novi, a town in the region that the Serbs hope to clear.

Jose Maria Mendiluce, the U.N. high commissioner’s special envoy, has described the paradox facing his agency.

“If we help the people go out, we are helping them (the Serbs) cleanse the areas,” he said recently. “If we don’t help them leave, there is a very dangerous situation.”

On July 28, Jean-Claude Concolato, then head of the high commissioner’s Zagreb office, said he was “outraged” at being “blackmailed” by Serbian militia commanders in Bosanski Novi into assisting in the removal of the Bosnian Muslims. “It was a shameful operation,” he said.

“All we can do,” Concolato said, “is make so much noise about it, to scream so loudly, that this will be the first and last time it happens.”

The tension in the Bihac area has been mounting steadily. The city has been without electricity and telephones for four months. Virtually no food supplies are getting in. Shops are closed, a meager farmers’ market sells only a few fresh vegetables (at rapidly escalating prices), and virtually no one works. New refugees arrive in the city daily, as do mortar rounds and artillery shells fired from the hills into the heart of the city.

“Some say we are in a very big concentration camp,” said Philippe Noel, head of the Red Cross in Bihac and in Velika Kladusa, the region’s other main city on the Bosnian-Croatian border.

As the Serbs were continuing to press their “ethnic cleansing” campaign in the Bosanska Krajina, the leadership of the rump Yugoslav nation appeared to be moving rapidly to clean out its most notorious prison camps and to allow relief supplies into the besieged Bosnian capital of Sarajevo, in an evident effort to stave off international intervention in the war.

The U.N. Security Council is to open debate today on a resolution that would authorize the use of force to ensure that relief supplies reach Bosnian civilians. A vote is expected Thursday. Also on Thursday, the U.N. Human Rights Commission in Geneva will take up reports of brutal conditions in Serbian-run Bosnian prison camps.

British Liberal Party leader Paddy Ashdown was taken on a closely supervised visit Tuesday to the Manjaca prison camp in northern Bosnia, where he found several hundred prisoners transferred in recent days from the notorious Omarska prison camp, whose former inmates have told of shootings, frequent beatings and near-starvation diets.

“Everyone I spoke to said conditions had clearly improved since they left Omarska,” Ashdown said. But he was allowed only about 30 minutes in the camp, and no prisoner got more than a few seconds to speak out of earshot of the guards.

Many of the prisoners, filmed by a television crew accompanying the British politician, were virtually skin and bones, and most seemed traumatized by their ordeal.

Representatives of the International Committee of the Red Cross were to begin inspecting some of the prison camps today, including Omarska, but it was widely believed that virtually all prisoners will have been removed by the time the Red Cross gets there.

In Washington on Tuesday, two very different generals--the Canadian who led the U.N. peacekeepers in Sarajevo and the assistant to Gen. Colin L. Powell, chairman of the Joint Chiefs of Staff--offered the Senate sobering views about military involvement in Bosnia.

Maj. Gen. Lewis MacKenzie of Canada, who led the U.N. peacekeepers until a week ago, described military intervention as nothing but “a carrot” for the Bosnian government.

The general told the Senate Armed Services Committee that the Serbs, since they now control sizable territory, are ready to sit down and negotiate with the Muslims who run the Bosnian government. But the Muslims refuse, MacKenzie said, because they hope that outside military forces will help them regain lost lands.

“My soldierly advice . . . is to get away from the carrot of intervention,” MacKenzie said.

He warned that any intervention of troops to protect humanitarian supplies would inevitably lead to even more intervention. “It can’t stop there,” he said. “It’s not a nice, neat little package.”

“There is no way that intervention will do anything but escalate the fighting,” MacKenzie said, “and more people will be killed. . . . What we need is intense political pressure to put the parties of the conflict in Bosnia-Herzegovina at the same table for an extended period of time . . . to grind out an agreement and come up with a constitutional solution.”

Replying to questions from the senators, Lt. Gen. Barry R. McCaffery, who is Powell’s assistant, said he believes it would take a field army of 400,000 troops one year to pacify Bosnia and lower the level of violence.

“It would take a considerable amount of time,” McCaffery explained, “because what we’re trying to destroy is not 4,000 tanks but the hatred of three peoples for one another.”

As for the more limited goal of guarding the Sarajevo airport and clearing a relief corridor of 200 miles from the Adriatic port of Split to Sarajevo, McCaffery estimated that would require 60,000 to 120,000 troops.

Meeting with reporters earlier, Sen. Sam Nunn (D-Ga.), chairman of the committee, said the Bush Administration should be giving further consideration to what he called “punitive strikes” and “demonstrations” designed to bring Serb-backed forces into line with the demands of Washington and the Europeans. Those strikes, conducted with Navy and Air Force aircraft, could aim at “knocking down bridges” and seek to “deprive (the Serbian forces) of the use of air power,” Nunn said.

“If you’re going to stop the fighting, you’ve got to go after the assets,” said Nunn, one of the Senate’s most influential members on military matters.

Meanwhile, flights bearing relief supplies have continued to arrive in Sarajevo, with total cargo running at a rate of about 200 tons daily. A U.N. spokeswoman in Geneva noted also that land routes are opening up to convoys bearing supplies from the Adriatic coast.

Serb and Bosnian forces signed an agreement Tuesday allowing more than 300 women and children to evacuate Sarajevo, wire services reported from the Bosnian capital.

A U.N. official said the three-way agreement to evacuate the women and children was signed by a Serbian liaison officer to the U.N. mission in Sarajevo, a representative of the Bosnian presidency and the Children’s Embassy, a charity group organizing the evacuation.

A spokesman for the charity said the evacuees, many of them shell-shocked from four months of urban war, would board buses this morning for Split.

In other developments:

* The Senate passed a resolution Tuesday calling on President Bush to seek from the United Nations “all necessary means, including the use of multilateral military force,” to ensure delivery of aid and access for inspectors to detention centers. The measure also called for the Security Council to find a way to bring artillery and other heavy weapons under U.N. supervision.

* Yugoslav President Dobrica Cosic asked the United Nations to send a commission of prominent figures led by Nobel laureate Elie Wiesel to investigate the detention camps. Wiesel said he will consider the offer but demanded complete freedom for his team.

Times staff writers Stanley Meisler and Melissa Healy in Washington contributed to this article.