Major Arvin Encinas of the military's Western Mindanao Command (Westmincom) said army scout rangers battled 40 militants near the village Bakong at around 1 p.m. on Sunday while trying to rescue five Indonesians and a Filipino doctor that Abu Sayyaf kidnapped last month and early this month.

Encinas said two militants were killed and the rest fled and were chased by the elite troops.

At least two army scout rangers were also injured in the clash, Encinas said.

"This is part of our rescue operation but we are not yet sure if this is the specific group holding the kidnap victims," he added.

Westmincom commander Lieutenant General Cirilito Sobejana said Sunday's encounter is an offshoot of the military's continued search and rescue operation to find all the hostages that Abu Sayyaf kidnapped last month and early this month.

On Jan. 16, Abu Sayyaf gunmen seized five Indonesian fishermen off Sabah in Malaysia and brought them to Sulu. Philippine troops recovered the boat the kidnappers used and killed one of their captors following a firefight in Sulare island in Parang town, Sulu two days later.

Abu Sayyaf gunmen also abducted a Filipino doctor in the remote Jolo town in Sulu Province on Feb. 4, bringing the total number of hostages to six.

Abu Sayyaf is considered the smallest but the most violent of the extremist groups in the southern Philippines. The group, which has an estimated 400 fighters, is active in the impoverished island provinces of Sulu and Basilan.

The group is responsible for the series of kidnappings-for-ransom, deadly bombings, ambushes of security personnel, public beheadings, assassinations, and extortion in the Mindanao region.

The group, which has been terrorizing the Philippine southern region since the 1990s, preys on foreign tourists, businessmen and fishermen not only from the Philippines but also from Indonesia and Malaysia and hide them in Philippine jungles or remote islands.