BELGRADE, Yugoslavia -- Sarajevo reverted yesterday to a rhythm of fierce shelling by night and uneasy calm by day. In Belgrade, tensions mounted after police threatened to break up a weeklong demonstration against President Slobodan Milosevic of Serbia.
Artillery fire on the Bosnia-Herzegovina capital was described as the heaviest since U.N. peacekeeping troops took control of the airport five days ago to allow humanitarian relief flights to the city, where at least 300,000 people have been holding out against a three-month Serbian siege.
Two soldiers of the 1,000-troop Canadian battalion that was deployed to secure the airport were slightly wounded by stray bullets from surrounding suburbs, Fred Eckhard, a U.N. spokesman, reported from Sarajevo.
"This has definitely been a setback for the airport operation," Mr. Eckhard said of the upsurge in fighting overnight. "It raises security concerns because the airport agreement starts with a reaffirmation of a cease-fire, and without that essential first step, all that is built on it stands on sand."
Western aid flights continued to touch down at Sarajevo's Butmir Airport and unload food and medicine for the city, which is on the brink of starvation.
But Mr. Eckhard said the commander of U.N. troops in Sarajevo, Maj. Gen. Lewis MacKenzie, was "monitoring the security situation closely and would turn back planes at a minute's notice if necessary."
The rain of artillery and mortars that flared after nightfall Friday and continued until dawn made clear that both the Serbian rebels attacking the city from its surrounding hills and Bosnian government forces responding from the valley were using heavy guns that they had not moved to U.N. monitoring sites.
General MacKenzie met with President Alija Izetbegovic of Bosnia and Serbian military commanders at their headquarters in the western suburb of Lukavica. He pressed them to comply with the airport agreement, which calls for all heavy artillery to be moved to sites under U.N. supervision.
"The lead is still flying at the airport as well," Mr. Eckhard reported from his station a few miles east of that facility. "Snipers are firing at each other over the runway, and yesterday around midday several bullets struck the terminal building where our people were working."
In Belgrade, the Tanjug news agency issued a report suggesting that city officials in the federal and Serbian capital would forcibly clear out an encampment of anti-government protesters if they refused to leave peacefully.
Hundreds of Serbs have pitched tents in Pioneer Park, across from the federal Parliament in the city's center and insist they will stay there until Mr. Milosevic resigns.
The protest began with 100,000 opposition demonstrators last Sunday.