Four Abu Sayyaf bandits were killed and one soldier died in a clash in Patikul town, Sulu on Saturday afternoon, the military confirmed.
According to Maj. Gen. Corleto Vinluan, commander of Joint Task Force Sulu, his office had received a tip that armed bandits were in Kabbon Takas village.
Troops then encountered the Abu Sayyaf, which led to a 30 minute gun battle. Four bandits were killed and four others were wounded.
The military, meanwhile, reported one fatality and four other soldiers hurt.
Troops recovered an M16 rifle and the bandits' personal belongings.
Vinluan said his command is verifying information that the brother-in-law of Abu Sayyaf leader Radulan Sahiron was among those killed killed.
The task-force commander said government troops did not run into the Indonesian fishermen abducted by bandits led by Hatib Hajan Sawadjaan, the self-proclaimed emir of the terror group Islamic State in the country.
Security forces are intensifying efforts to rescue the 3 Indonesian citizens abducted off Sabah, Malaysia in September.