SIDON, LEBANON, JULY 22 -- Iranian-backed Hezbollah fundamentalists today crushed a joint attack by rival Shiite Moslems and Palestinian guerrillas, capping two days of combat at Jarjou, a mountaintop town in southern Lebanon, that killed 52 people and wounded 135, police said.

The new casualties raised the toll of the week of clashes between the Syrian-backed Amal and Hezbollah to 125 killed and 367 wounded.

The two factions have been fighting each other intermittently for three years for leadership of Lebanon's 1.2 million Shiites. By police count, at least 1,166 people have been killed in the power struggle.

Hezbollah claimed today to have "regained the whole of Jarjou from Amal and the mercenaries." Amal said it still held a quarter of Jarjou, but police and reporters said Amal and PLO fighters had withdrawn from the town.

The term "mercenaries" appeared to be an allusion to a 600-member force of Palestine Liberation Organization guerrillas sent to the region ostensibly to halt the fighting. Police said the PLO force, drawn mainly from Yasser Arafat's Fatah faction, became actively involved on Amal's side after Hezbollah attacks killed three guerrillas on Friday.

An estimated 250 PLO fighters teamed up with 300 Amal militiamen in an assault on Jarjou on Saturday. Hezbollah had taken the town from Amal at the outbreak of the latest round of fighting last Monday. A police spokesman said casualties among PLO fighters since their deployment Tuesday were nine killed and 23 wounded.