SIDON, LEBANON, SEPT. 9 -- Fierce fighting between rival Palestinian factions in this southern port city subsided today after three days of violence in which at least 64 people were killed and 278 wounded, security sources said.

Hospital sources said the casualty toll may climb because "there could be more bodies under the rubble."

Fighters loyal to Palestine Liberation Organization Chairman Yasser Arafat had been seeking since Friday to drive guerrillas of the Fatah Revolutionary Council led by Abu Nidal out of the area, but the two sides disengaged in midafternoon today, the security sources said.

The sources said at least three people were killed and 20 wounded in today's fighting. Rocket, artillery and mortar exchanges forced about 5,000 families to flee Sidon, 25 miles south of Beirut.

Witnesses said thousands of people emerged from underground shelters after the cease-fire to inspect damage to their homes.

The security sources said Arafat's guerrillas had taken control of the Ain Hilweh refugee camp near Sidon, the biggest in south Lebanon, but Abu Nidal's gunners still held positions in hills overlooking the city.

"It is still not clear yet if Arafat's men will chase Abu Nidal's people into the hills," one source said.

{Younis Awad, a senior Arafat aide, told the Associated Press that the PLO controlled all of southern Lebanon and that Abu Nidal's forces were "finished. It's a final victory."}

The PLO fighters have vowed to drive Abu Nidal's forces from the area.

Abu Yasser, Arafat's top military aide in Lebanon, said the Fatah Revolutionary Council had been behind the abduction of several Westerners. "The kidnapping of two Swiss workers, some French . . .affected the city of Sidon and the Palestinian cause," he said. "For a few dollars only they do such crimes in the name of the Palestinian people."

The PLO issued a death sentence 16 years ago against Abu Nidal, whose real name is Sabri Banna, accusing him of plotting to kill Arafat. Abu Nidal broke with Arafat's Fatah movement and formed the FRC, which staged attacks on Israeli and Western targets in Europe in the 1980s. Abu Nidal is wanted by the United States and some West European nations in connection several such attacks.