Yasser Arafat's guerrillas Monday held off Syrian-backed PLO dissidents seeking to storm the Arafat loyalists' last Beirut stronghold. Police said at least 21 people were killed and 67 wounded.

Six hours of fierce fighting, which included rocket barrages and mortar fire, began at dawn in the Bourj el-Barajneh refugee camp.

The latest casualties raised the toll to at least 148 killed and 594 wounded since battles broke out May 1 between Col. Saeed Mousa's dissident Fatah-Uprising faction and Arafat's Fatah group.

Monday's fighting ended a weeklong lull in the battle between the rival factions for control of Beirut's two remaining Palestinian refugee camps.

Police said 20 rounds a minute were exploding Monday in the sprawling shantytown on Beirut's southern outskirts.