Bush Demands That Serbs Halt Civilian Slaughter : Balkans: President vows tighter curbs on Belgrade, OKs full diplomatic relations with Bosnia, Slovenia and Croatia. He calls for U.N. force to secure relief effort.

President Bush demanded Thursday that Serbian military forces end their “vile policy of ethnic cleansing, deliberately murdering innocent civilians,” but he said his Administration will not use military force in the Balkans except to ensure the delivery of food and medicine.

Speaking out on the bloody warfare in the former Yugoslav republics for the first time since reports surfaced that the Serbs were operating ethnic concentration camps, Bush vowed to tighten the economic, political and diplomatic isolation of Serbia and extended full diplomatic relations to its foes in Bosnia-Herzegovina, Slovenia and Croatia.

He said it is “absolutely critical” that the U.N. Security Council authorize the use of military force, if necessary, to get relief supplies to Sarajevo and other besieged cities in Bosnia. U.S. diplomats have been seeking such a resolution for several days. But Bush conceded that the effort has run into opposition from some nations on the 15-nation council.

In an apparent rebuttal to Democratic candidate Bill Clinton’s call for American bombing raids on Serbian positions, Bush emphasized the pitfalls of outside intervention--except to ensure the delivery of food and medicine--in what amounts to European tribal warfare.

“Those who understand the nature of this conflict understand that an enduring solution cannot be imposed by force from outside on unwilling participants,” he said. “The blood of innocents is being spilled over century-old feuds. The lines between enemies and even friends are jumbled and fragmented.

“Let no one think there is an easy or a simple solution to this tragedy,” Bush said. “The violence will not end overnight, whatever pressure and means the international community brings to bear. Blood feuds are very difficult to resolve. Bringing peace again to the Balkans will literally take years of work.”

Bush conceded that there is no proof that some of the detention centers run by Serbian militias in Bosnia have been turned into concentration camps in which Muslim Slavs and Croats are being tortured and put to death. He said he has instructed U.S. intelligence agencies “to use every asset available to see if we can confirm” the reports. In addition, he demanded that the International Committee of the Red Cross be permitted to inspect detention facilities run by all factions of the complex war.

“To truly end the humanitarian nightmare, we must stop ethnic cleansing and open any and all detention camps to international inspection,” Bush said. “We will not rest until the international community has gained access to any and all detention camps.”

At the Pentagon, where military officials have demonstrated deep reluctance to be drawn into the conflict, spokesman Pete Williams acknowledged that satellites and spy planes have been mobilized to search for evidence. But he stressed that so far, intelligence efforts have failed to turn up any death camps.

In Geneva, a Red Cross spokesman said the warring factions in Bosnia continue to refuse to allow inspections of most internment camps, even though leaders of all factions insist that they have nothing to hide and say that visitors will be welcome.

In London, the European Community added its weight to the demand for outside inspections of the detention camps. A statement issued by the British-held EC presidency condemned the camps as “repulsive and despicable.”

At U.N. headquarters, Secretary General Boutros Boutros-Ghali said he does not want to get U.N.-sanctioned military forces involved in any sort of combat in Bosnia.

Interviewed by The Times, Boutros-Ghali said: “Who will make up this force? That is the big question. If it is NATO, OK. But I cannot do it myself.”

As if hearing his words, members of the North Atlantic Treaty Organization meeting in Brussels agreed Thursday to draw up plans that could involve thousands of Western troops in ensuring that humanitarian aid is delivered to the former Yugoslav republics, NATO sources told Reuters news agency.

NATO’s military authorities will be formally asked next week to work out contingency plans including the possibility of opening up a land corridor from the Adriatic Sea to the beleaguered Bosnian capital of Sarajevo for armed relief convoys--an operation that, in the opinion of NATO leaders, might require up to 100,000 troops, Reuters said.

A political decision to use force would have to be made before any of the plans are put into effect, and a mandate from the United Nations would be needed, the sources said.

Administration officials have complained that both Britain and France--probably Washington’s closest allies--have resisted the use of force. In his impromptu press conference, Bush cited no nation by name, but he acknowledged that some U.S. allies are extremely reluctant.

“But we’ve got to get them together,” he said. “I think there is increasing concern on the part of our allies, and so we are taking the lead in trying to get that done.”

Bush delivered his statement on short notice after days of near-silence on the issue. On a campaign trip Wednesday, he had dodged shouted questions about the crisis and made no mention of the conflict even in a foreign policy speech.

His abrupt decision to speak out appears to have been prompted both by the increasingly vocal calls for action from congressional Democrats and by the increasingly gory news footage being broadcast from the splintered remnants of Yugoslavia.

The Administration had already recognized the independence of the breakaway Yugoslav republics of Bosnia, Croatia and Slovenia but had withheld diplomatic ties. Bush’s announcement Thursday that he would soon name American ambassadors to the three states amounted to a final acknowledgment that the breakup of Yugoslavia is irreversible.

Meanwhile, British television teams were allowed to visit an internment camp run by Serbian forces near Omarska in Bosnia. They reported that the prisoners seemed emaciated and frightened.

Milan Panic, the Southern California businessman who is serving as prime minister of the Serbia-Montenegro federation that still calls itself Yugoslavia, said he visited all detention centers in the two republics and found conditions to be good.

Interviewed on CNN, Panic said it is possible that conditions are much worse at camps run by Serbian forces in Bosnia. “But I cannot go to check the camps in another country,” he said.

In another development Thursday, the Vatican said that Europe and the United Nations have the duty to intervene in Bosnia. Cardinal Angelo Sodano, the Vatican’s secretary of state, said that after discussing Bosnia with Pope John Paul II, he believes that “the European states and the United Nations have the duty and the right to interfere, to disarm one who wants to kill. This isn’t favoring the war, but impeding war.”

Kempster reported from Washington and Jehl from Colorado Springs. Also contributing were Times staff writers Stanley Meisler at the United Nations, Melissa Healy in Washington and William Tuohy in London.