Shiite Moslem militiamen and Palestinian forces fought today for control of three major Palestinian refugee camps on the southern edge of Beirut in fierce battles that killed at least 52 persons and wounded 250.
The fighting appeared to be a move by the Shiites, one of Lebanon's strongest military forces, to prevent the Palestinians from reestablishing themselves in strength here and in southern Lebanon, where the Shiites fear that a hostile Palestinian presence could invite Israeli reprisals.
Armed Palestinian fighters have been infiltrating back into the camps from Syrian-controlled territory in eastern Lebanon recently, and some Shiite officials hinted today that the current offensive was intended to broaden the dispute by drawing Syria into it to force a resolution.
Fighters of Amal, the militia of the mainstream Lebanese Shiite movement and the country's dominant Moslem military force, encircled the Sabra, Shatila and Burj al Barajinah camps on the capital's southeast edges today. After 20 hours of fighting, Amal said it had taken control of Shatila and sealed off Sabra.
Sabra and Shatila, then within the area controlled by Israeli invasion forces, were the scene of a massacre in September 1982 of hundreds of Palestinians and Lebanese Moslems by Christian militiamen enraged at the assassination of president-elect Bashir Gemayel, a Christian.
Today's barrage of mortars, rocket-propelled grenades and antiaircraft shells paralyzed Beirut and hampered air traffic at Beirut's international airport. Amal gunners fired into the besieged camps from elevated positions, while guerrillas put up stiff resistance.
Troops of the Lebanese Army's 6th Brigade, which is mainly Shiite, were in the area, but their role was unclear. Several witnesses reported seeing them shelling the camps.
The fighting began in Sabra. Palestinian sources said Amal representatives have been rounding up guerrillas at random for questioning, and when a Palestinian was brought back last night, evidently badly beaten, a quarrel erupted and esclated rapidly into a noisy showdown.
Palestinian fighters spread outside the camps into the Fakhani neighborhood, once almost exclusively Palestinian, which housed offices of the Palestine Liberation Organization and its chief, Yasser Arafat, in the heyday of the PLO here, before its grip was broken by the Israeli invasion.
Amal, led by Nabih Berri, who also holds a Cabinet position as minister of justice and state minister for southern Lebanon, is determined to prevent a resurgence of Palestinian guerrilla power. Since February 1984, it has tried to keep a firm grip on the camps by posting checkpoints at its exits and making unannounced weapons searches.
Amal fears that a Palestinian comeback could lead to unbridled guerrilla activity, weaken the Shiites' hold on their home territory in the south and invite Israeli retaliation, while the local population is still recovering from past reprisals.
Walid Jumblatt, leader of the Druze militia and also a Cabinet minister, stayed out of today's conflict, although he has been Berri's closest ally and both have been closely associated with Syria. Their militias joined forces last April to crush the Sunni Moslem Mourabitoun militia backed by Palestinian guerrillas loyal to Arafat, but Amal officials now charge that Palestinian guerrillas have been returning to the camps here through the Druze-controlled hills east of the city.
Sheik Abdel Amir Qabalan, the mufti of Lebanon's Shiite Moslems, speaking at a rally commemorating the death of four Amal members killed in operations against Israeli soldiers, said this weekend that the days of the PLO in Lebanon were a thing of the past.
"The era of the 'Abus' is over," Qabalan said, in a mocking reference to Palestinian guerrilla code names such as Abu Ammar, Abu Jihad, and Abu Iyad.
Palestinian fighters interviewed in the camps today said the Amal offensive has had the effect, at least there, of reuniting pro-Syrian guerrillas who oppose Arafat and Arafat loyalists, who have been bitter rivals since 1983.
"We are all Palestinian, surrounded by one enemy," one fighter said. "All the differences between the . . . factions have been erased. We are all fighting against Amal."
Berri conferred by telephone with Syrian Vice President Abdul Halim Khaddam today and sent an envoy to Damascus. Syrian-backed militiamen in jeeps were seen at the northern entrance to one of the camps.
Lebanon's beleaguered Sunni Moslems have been urging Syria to intervene in Lebanon with the hope that it would put an end to supremacy of the once small Shiite community, which has overwhelmed and outnumbered them in Beirut.