Relief Nears as Sarajevo Truce Holds : Balkans: U.N. Security Council could authorize 1,000 Canadian troops to secure the airport.

BELGRADE, Yugoslavia —  A frail cease-fire held in Sarajevo on Tuesday as U.N. peacekeepers prepared to enter the besieged Bosnian capital to help set up an airlift of food and medicine for thousands of trapped civilians.

In New York, the U.N. Security Council was due to convene to evaluate a peacekeepers’ report on the situation in Sarajevo. It could authorize 1,000 Canadian troops to secure the airport if it deems the truce durable.

Fred Eckhardt, spokesman for the U.N. Protection Force in Belgrade, said the 47-vehicle convoy passed the main Serb militia checkpoint at Pale outside Sarajevo without problems.

The convoy, which set out from Belgrade before daybreak, included 60 military observers assigned to Serb artillery positions outside Sarajevo to deter firing that could endanger relief flights.

Minority Serbs, who have besieged Sarajevo since rebelling in March over Bosnia-Herzegovina’s secession Feb. 29 from the Yugoslav federation, accepted a U.N.-mediated truce Sunday but continued to seal off Sarajevo by land.

Reporters in Sarajevo quoted Bosnian President Alija Izetbegovic as saying his troops would cooperate with the Croatian army in battling Serb irregulars.

He also promised to get the airport open. “If we don’t open it by negotiations, we will open it by force,” he was quoted as saying.

Buoyed by the cease-fire, which came into force Monday morning, U.N. peacekeeping representatives were negotiating to have Serb forces relinquish the airport to U.N. troops.

“There is sporadic shooting, but we’ve had very good cooperation from both sides in detailed discussions on reopening Sarajevo airport,” Eckhardt said.

Sarajevo journalists described the truce as precarious, citing sporadic shelling and sniper fire directed at civilians.

Bosnia’s government crisis center said four people had been killed and 31 wounded Tuesday, mostly by snipers who have ignored the cease-fire in some contested districts.

Heavy fighting raged in Mostar, an ethnically mixed town 50 miles southwest of Sarajevo, the Belgrade-based Tanjug news agency said.

Sarajevo news media said two news photographers, identified as Jana Schneider of the United States and Ivo Standeker of Slovenia, were wounded by shelling from Serb positions.

At the United Nations, Bosnia’s ambassador, Mohamed Sacirbey, said his chief of staff told him that Serb forces killed at least 46 people in a bus attack outside Sarajevo Tuesday.

But Sacirbey said he was seeking further verification of the incident. The report could not be independently confirmed. U.N. officials were looking into the claim, but noted that previous Bosnian reports were exaggerated.

U.N. Secretary General Boutros Boutros-Ghali told the Security Council Tuesday that he would not endorse sending peacekeepers to guard Sarajevo’s airport until he was certain the truce was solid.

He said a “definitive agreement” on transferring the airport from Serb to U.N. peacekeeping control was expected to be signed shortly with Serb leaders in Bosnia.