Desperate Sarajevo Neighborhood Gets Relief : Balkans: Fighting eases briefly in Bosnian capital, but brutal bombardment continues in other cities.

International relief agencies took advantage of a brief cease-fire to get aid into the most desperate neighborhood of besieged Sarajevo on Sunday, but intensified fighting elsewhere flattened any hopes that the vicious war in Bosnia-Herzegovina is waning.

Serbian guerrillas have surrounded the eastern Bosnian city of Gorazde with tanks and heavy artillery and unleashed a fierce bombardment against tens of thousands of trapped Bosnian Muslim refugees, Sarajevo Radio reported.

A two-day assault on Gorazde has prompted Bosnian President Alija Izetbegovic to appeal to the U.N. Security Council to stop what he fears is a massacre of fellow Muslims.

Gorazde’s population has been swollen to more than 70,000 by Muslims driven from homes elsewhere in the embattled republic during more than three months of Serbian rebellion against Bosnian independence. At least 7,500 people have died, and Yugoslavia’s refugee wave now exceeds 2.2 million.

Relief officials in this Adriatic port city, which has become a base for delivering food and medicine to southern and western areas of Bosnia-Herzegovina, also reported that Serbian forces have recaptured territory around the shattered city of Mostar.

Cyrus Shakhalili, an Iranian official of the U.N. refugee agency, said Serbian forces have taken back the eastern bank of the Neretva River at Mostar, a once-scenic city of ancient mosques and a 400-year-old Turkish bridge that is a key point along the supply line to western Bosnia-Herzegovina.

Renewed fighting between Serbian rebels and the Muslim and Croat forces supporting the Sarajevo government also flared in Bihac, west of Sarajevo, and in the northern Bosnian city of Gradacac.

Near the Adriatic resort of Dubrovnik in Croatia, television showed footage of twisted cars and churned-up earth in what it described as the third day of Serbian shelling of the ancient walled city. But the shells appeared to have fallen considerably south of the famed resort, closer to the Prevlaka peninsula bordering Montenegro that has been the scene of intense Serb-Croat fighting for nearly a year.

While clashes continued to intensify elsewhere, Sarajevo was reported to be relatively calm as both sides respected a morning cease-fire to allow a dozen trucks bearing food and medicine into the suburb of Dobrinja.

Although only a few hundred yards away from Sarajevo’s Butmir Airport, Dobrinja’s more than 30,000 holdouts had been cut off from the aid shipments that have been flown into the Bosnian capital daily since a U.N.-protected humanitarian airlift began June 29.

After days of pressure from U.N. mediators, the Serbian rebels and Bosnian government forces agreed to a three-hour cease-fire to protect the volunteers bringing in aid.

The 12 U.N. trucks unloaded their cargo without incident, but Sarajevo Radio reported that sniper fire broke out immediately after the mission was completed.

In isolated instances, humanitarian aid convoys braving snipers and persistent outbreaks of shelling have helped to relieve the suffering of Bosnian civilians, most of whom have been prevented from working or tilling their fields since civil war broke out after a Feb. 29 independence vote.