ASSOCIATED PRESS WRITER

SNJEZANA VUKIC

MOSTAR, Bosnia-Herzegovina (AP)—Muslims fearing renewed Croat attacks kept a U.N. convoy from leaving Mostar Thursday after the trucks brought the first food and medicine to the besieged population in two months.

The 19-truck convoy planned to stay in Mostar’s Muslim eastern sector overnight ‘‘unless some miraculous decision comes,’‘ said a U.N. official reached by telephone in the nearby town of Medjugorje. The official spoke on condition of anonymity.

The convoy arrived in the southwestern Bosnian city late Wednesday to aid 55,000 Muslims reported near starvation from a Croat siege. U.N. officials found bone-thin people huddled 100 to a cellar for protection from shelling, and buildings pocked by shellfire.

But when the convoy tried to leave early Thursday, rag-tag soldiers fired in the air and barricaded the road out with a bus. Hundreds of women and children pleaded for the convoy to stay, convinced that the U.N. presence could protect them.

‘‘If you leave, they are going to massacre us!’‘ cried one woman, who identified herself only as Almira, 32.

The Muslims made demands, including that children be evacuated, and there were reports that two Muslim children would be taken out.

Bosnia’s Muslim president, Alija Izetbegovic, appealed to the Muslims to let the U.N. convoy leave, Sarajevo radio reported Thursday night.

Sporadic shelling hit the Muslim sector Thursday, and wounded people were brought to the city’s only hospital. Two people were killed by snipers. The convoy was not hit, officials said.

Once allies, Croats and Muslims have fought bitterly for Mostar and for land in central Bosnia, and the fighting has worsened as leaders of the warring factions come closer to agreeing to a peace plan dividing the country. Croats want to make Mostar the capital of a Bosnian Croat state.

After spending days in Medjugorje because Bosnian Croats refused to grant it clearance, the convoy took hours to get to Mostar because Croat women sat in its way to keep aid from reaching the Muslims.

Upon arriving in Mostar, thousands of exhausted people mobbed the trucks as they pulled to a stop. The crowd pounded on truck windows, demanding cigarettes and chocolate.

The convoy brought 175 tons in basic drugs, powdered milk, baby food and other food into the eastern sector, while about 90 tons went to the Croat-controlled west bank of the Neretva River.

Dr. Zlatko Guzin said the Mostar hospital, which can only be approached over a square open to Croat snipers, had one day’s supply of blood left and had run out of oxygen and other essentials.

After unloading its supplies, the convoy prepared to return to its base in Metkovic, Croatia, but was mobbed by Muslims.

Cedric Thornberry, the U.N. civic affairs officer for former Yugoslavia, negotiated for hours with local officials and reached agreement to get the trucks out. At one point he angrily threatened to stop all humanitarian aid to Bosnia otherwise.

Thornberry said the convoy and its personnel were ‘‘held as hostages, which is completely unacceptable.’‘

Despite the accord, in midafternoon dozens of residents staged a sit-down strike in front of the vehicles. Some sat on chairs, others on blankets. New negotiations between Thornberry and local officials followed and new conditions were set.

One condition reportedly was that wounded children be evacuated, and a report said that two children would be. One, a 10-year-old girl, had lost her right arm and suffered serious facial injuries. The other, a boy identified as Mirsa Handari, had a wounded leg.

An earlier demand for a permanent U.N. and High Commissioner presence in Mostar was dropped, the official in Medjugorje said.

Before Izetbegovic issued his reported appeal, a U.N. statement issued in Zagreb said a senior U.N. official visiting Sarajevo urged him to intervene.

Earlier Thursday, Kofi Annan, U.N. assistant secretary-general for peacekeeping operations, reportedly told Izetbegovic the U.N. relief mission’s work ‘‘is being impeded by the very people they went there to help.’‘

Despite the troubles, Peter Janssen, spokesman in Sarajevo for the UNHCR agency, said another convoy would be sent as soon as possible.

U.S. airdrops into Mostar, meanwhile, continued with a drop of 31 tons of food early Thursday, the U.S. military in Frankfurt, Germany said.

In other developments, Yugoslav leaders bowed to ultra-nationalist pressure Thursday and fired the country’s moderate military chief, replacing him with a general who ran ruthless military campaigns in Croatia and Bosnia.

In a major purge of the army command, 42 other generals were retired along with Gen. Zivota Panic, chief of the general staff, said a statement by the Supreme Defense Council. Gen. Momcilo Perisic replaced Panic.

The 17-month-old war has killed as many as 200,000.