Serb gunners pounded the eastern Muslim enclave of Gorazde and stepped up shelling of Sarajevo on Monday as the U.N. peacekeeper commander arrived in the capital hoping to arrange a truce.
Fighting between Bosnian Croats and Muslim-led government forces also moved closer to Sarajevo, with the one-time allies battling along the road to Kiseljak west of the capital.
"This is the first time we've seen this kind of shelling concentrated in this area," said Cmdr. Barry Frewer, a spokesman for U.N. peacekeepers. "We don't know whether it is the shape of things to come."
But U.N. concern remained focused on Gorazde, where as many as 70,000 residents and refugees have been isolated for months and hammered for the past 18 days by besieging Bosnian Serbs.
Gorazde is one of six towns designated as "safe areas" by the United Nations, but Serbs so far have refused to allow U.N. observers to enter the town, which is the last eastern enclave held by Muslim-led troops.
Bosnian Serbs, who control about 70 percent of Bosnia, seek unchallenged authority over the eastern area.
"We are looking into Gorazde today, and we do hope that we will get some more information from that area," said Swedish Gen. Lars-Eric Wahlgren, commander of all U.N. peacekeeping forces in Yugoslavia and its former republics.
In a related development, a U.N. Secretariat report obtained Monday by Associated Press said that the world body tentatively plans to send at least 7,500 troops _ and possibly more _ to enforce the safe areas.
The report said the troops would be armed and authorized to fire their weapons if they or their charges were endangered.