Serb Militia Chief Says He’ll Beat U.N. Arms Deadline : Bosnia: But shelling resumes after a morning lull in Sarajevo. Food stocks could run out by Thursday.

Bosnia’s Serbian leader promised Monday to beat a deadline to put heavy guns under U.N. supervision, but shells still rained on Sarajevo and officials said the city could run out of food stocks by Thursday.

With five days left before the noon Saturday deadline agreed to at London peace talks last month, shelling resumed after a morning lull and closed the airport used by U.N. planes, officials said.

No casualties were reported at the airport, but Bosnia’s Health Ministry reported Monday that 13 died and 77 were wounded in fighting in Sarajevo.

An airlift using Western air force planes to ferry humanitarian aid was suspended Thursday after an Italian transport plane was downed approaching the capital, killing all four crew members.

Under a London agreement last month, Serbian militias are to gather their tanks, rocket launchers, field guns and large-caliber mortars surrounding the Bosnian capital, the eastern town of Gorazde, and Bihac and Jajce to the west, for monitoring by U.N. officers.

Cyrus R. Vance and Lord Owen, co-chairmen of a continuing Yugoslav peace conference in Geneva, on Sunday announced the deadline set for Saturday but did not say what would happen if Bosnian Serbian leader Radovan Karadzic did not comply.

“We will put our artillery around Bihac, Jajce and Sarajevo under the U.N. control before the deadline,” Karadzic said in a telephone interview Monday from his headquarters in Pale, east of Sarajevo.

He said there was no need to concentrate weapons around Gorazde, because Serbian forces already “abandoned” the town after a bitter, five-month siege.

U.N. officials said Monday that no weapons had yet arrived at the predesignated collection sites.

“As yet the weapons have not started moving toward their locations,” said Fred Eckhard, U.N. spokesman in Geneva.

Vance, a former U.S. secretary of state, and Owen, formerly British foreign secretary, plan to travel to the region this week. Eckhard said one of their priorities will be to find ways to resume humanitarian flights.

The estimated 350,000 people left in Sarajevo have relied on the airlift for food and medicine since June. Without it, food reserves would be gone “by September 10,” warned Sylvana Foa, spokeswoman for the Office of the U.N. High Commissioner for Refugees.

U.N. experts and envoys from the warring factions held an emergency meeting Monday in Geneva on how to keep other planes from being shot down. U.N. and European Community officials set another meeting for Wednesday.

Heavy artillery duels between Serbs and Bosnian government forces raged over central and western Sarajevo on Monday. The Belgrade news agency Tanjug said Bosnian forces attacked Serbian troops in the western suburb of Nedzarici, near the airport.

There, U.N. officials said shells crashed close to the control tower, forcing them to close the runway even to the distinctive white U.N. planes that transport supplies and personnel only for peacekeeping operations.

Water, a scarce commodity for months, was restored only to U.N. headquarters and a western district after negotiations between government and Serbian officials.