Bosnia Peace Pact to Require 65,000 Troops, U.N. Is Told : Balkans: Mediator Stoltenberg insists that the republic’s Muslims have little choice but to sign.

Mediator Thorvald Stoltenberg urged the Security Council on Monday to plan for an army of perhaps 65,000 to police and implement a peace proposal that could at long last end the cruel war in Bosnia-Herzegovina.

The peace plan, accepted by Bosnian Serbs and Croats, has still not won acceptance from the Muslims. But Stoltenberg, the U.N. special envoy on the former Yugoslav federation, insisted that they have little choice.

“The choice we face now is between a negotiated peace and a continued and intensified war,” Stoltenberg, a former Norwegian foreign minister, told the council ambassadors.

The Muslims, he told reporters later, will lose their last chance for a negotiated settlement if they refuse to accept the plan by next Monday, the deadline set by Stoltenberg and his fellow mediator, Lord Owen, a former British foreign secretary and now the European Community’s Yugoslav mediator.

But Venezuelan Ambassador Diego Arria said he had argued at the closed-door council meeting that the choice must not be limited to acceptance of the plan or war. “There should be a third option,” he said. “The Security Council and the international community should not stand idly by if one side chooses continued war.”

The council, however, has long opposed trying to put down Serbian aggression by force. Most ambassadors were obviously in favor of approving the peace plan, if finally accepted, no matter how reluctantly, by the Muslims.

U.S. Ambassador Madeleine Albright, the Security Council president for this month, said members had spent much time discussing the need to get ready for the peace plan. “If the parties do agree,” she said, “implementation will be on everyone’s mind after next Monday.”

Stoltenberg said he had told the council that planners believed that about 40,000 U.N. peacekeepers would be needed to augment the 25,000 on duty now in former Yugoslav republics.

Although the United Nations has had difficulty recruiting forces to defend the besieged U.N.-declared safe areas of Bosnia, Stoltenberg said: “I believe that if we get the peace agreement, the governments will be more open to giving us the troops.”

He said that, once an agreement was signed, the United Nations could quickly redeploy many of the 25,000 peacekeepers now in the area while waiting for the arrival of the additional 40,000.

The Clinton Administration has said it would consider sending troops to Bosnia to implement a peace agreement there. But it has never made any public pledge to do so. At present, Americans on duty in the former Yugoslav federation include a contingent of 300 troops in Macedonia.

Several Security Council members have been troubled by the Stoltenberg-Owen negotiations in Geneva because they seem to reward Bosnian Serbs for aggression and “ethnic cleansing”--their largely successful attempt to drive Muslims out of Serbian-held areas.

The map, drawn up by mediators, would call for a withdrawal of Serbian forces to allow Muslims control of 31% of Bosnia. But this is far less than the size of the Muslim-dominated areas before the war or the areas designated for Muslims in previous peace proposals.

Some ambassadors also complain that the mediators have failed to keep them informed about happenings in Geneva. Stoltenberg, a U.S. diplomat said, came to New York only because he was summoned by Albright.