The Philippine military says Abu Sayyaf guerrillas have killed at least six soldiers who were guarding a road project that has been delayed by militant attacks in the country's impoverished southern region.

Army Col. Rolando Bautista says the soldiers were patrolling the outskirts of a farming village on Basilan island's Sumisip town Sunday when about 20 heavily armed Abu Sayyaf fighters opened fire, sparking a 45-minute battle.

Bautista says he deployed additional troops to pursue the attackers.

The attack came as hundreds of troops hunted down Abu Sayyaf gunmen after they freed two German tourists last month on nearby Jolo Island, reportedly after a huge ransom payment.