ABRA, Lebanon (AP) _ Jubilant Christian militiamen withdrew Tuesday from five hilltop positions overlooking Sidon after nearly a month of fighting that left at least 113 people dead.

Police said a Palestinian guerrilla and a Lebanese soldier were killed in a gunfight with the withdrawing Christians of the Lebanese Forces militia at the Mieh Mieh refugee camp and several other combatants were wounded.

The Christian militiamen, led by Gilbert Ghostine, had been ordered from their home base in Beirut to the area around Sidon, 25 miles south of the Lebanese capital, to support local Christian forces battling Moslem militias.

Ghostine called the 26-day siege of Sidon a ''military victory.''

He said his 450 militiamen will return to Beirut by Wednesday after vacating four other posts, leaving local militias in Christian-controlled villages to garrison their areas.

Ghostine claimed ''less than 10'' Christian fighters and civilians were killed in Abra, one of his militia's main bases, during the fighting that began March 29.

Police reported 113 deaths and said 450 people were wounded in the battles in and around Sidon.

There were these other developments:

-In Tel Aviv, the Israeli military command reported its troops killed two guerrillas in a fight Tuesday at Mt. Barouk in central Lebanon. It did not mention any Israeli casualties.

The gunfight occurred as reports circulated that the Israeli were preparing to withdraw within a few days from the eastern sector, where they face Syrian army units. Israel invaded Lebanon in June 1982 in a campaign against Palestinian guerrillas, and the Cabinet announced Sunday that all of the Israeli forces would be out of Lebanon by the beginning of June.

-The Lebanese army's 1st Brigade, a Syrian-trained force of about 1,000 men, began deploying in the eastern Bekaa Valley in preparation for the Israeli withdrawal.

-Twelve religious and political leaders of the Moslem Sunni, Shiite and Druse sects met in Damascus, Syria, with Vice President Abdel-Halim Khaddam in a new effort to end the fighting between their militias in predominantly Moslem west Beirut.

Lebanon's Sunni prime minister, Rashid Karami, declined to give details, but told reporters in Damascus, ''We hope the results will be encouraging.'' He then left to return to Beirut.

Some 40 people were killed and 170 wounded last week in fighting between the rival militias to gain control of west Beirut.

Karami and his year-old coalition Cabinet resigned last Wednesday because of the battles pitting the Shiites' Amal militia and Druse fighters against Sunnis' Mourabitoun militia. He agreed to remain in office in a caretaker status.

Syria, the main power broker in Lebanese politics, wants Karami to stay on, and Beirut radio stations reported he was expected to withdraw the resignation.

The battle at the Mieh Mieh refugee camp broke out as Palestinian guerrillas, Moslem militiamen and Lebanese troops tried to advance on positions being evacuated by Christian militias east of sidon.

It violated a cease-fire called by the Lebanese Forces commander, Samir Geagea, Monday in advance of the withdrawal of the Beirut militiamen.

The plan to evacuate some of the Christian fighters aboard a freighter to Beirut was postponed for at least 24 hours when the vessel was unable to dock because of heavy seas, Christian officials said.

Reporters at the scene said some militiamen were angry when the freighter's captain refused to dock, and one fired at the ship.

Christian officials said most of the ''Lebanese Forces'' fighters were regrouping near Jieh, six miles north of Sidon.

Lebanese army commanders ordered the estimated 2,000 soldiers of the reinforced 12th Brigade based in and around Sidon to take over security from Moslem militias as the Christians withdrew ''to ensure the protection of all citizens.'' The army had taken little part in the fighting.