MANILA, Philippines (AP) — The Philippine military says Muslim militants have ambushed security guards and laborers from a rubber plantation on a volatile southern island, killing three men and wounding six others.

The attack Thursday on Basilan Island, the stronghold of al-Qaida-linked Abu Sayyaf militants, is the latest in weeklong assaults against the 1,200-hectare (2,964-acre) plantation despite the military’s efforts to protect workers.