MANILA, Sept. 23 (Xinhua) -- The Philippine military authority is mulling to send extra combatant troops to a remote southern island where at least three commanders of the Islamic militant group Abu Sayyaf are hiding, a military official said Wednesday.

    Lt. Col. Romeo Brawner Jr., chief spokesman of the Armed Forces of the Philippines, said the military is planning to send troops to Jolo Island, some 950 kilometers south of Manila, as the latest clashes indicated that Isnilon Hapilon, a top wanted Abu Sayyaf leader, has come to Jolo from his base in the neighboring island of Basilan.

    Fire-fight broke out as soldiers tracing Hapilon on Sunday stumbled on a hidden rebel camp in the jungles of Jolo. At least 19 suspected members of the Abu Sayyaf were killed while five soldiers were wounded in the clash. On the following day, retaliating militants ambushed a Marine convoy, killing eight soldiers.

    Brawner said more than 220 rebels gathered as Hapilon met with two other prominent Jolo-based Abu Sayyaf leaders, Albader Parad and Dr. Abu.

    Founded by a radical Islamic scholar in late 1980s, the Abu Sayyaf is known to have received assistance from the al Qaeda network in its early days. The group, with fewer than 400 members now, is blamed for the most deadly terrorist attacks and a series of kidnapping for ransom in the Philippines.

    Military officials also announced on Wednesday that three school teachers being held hostage by Abu Sayyaf militants for six months, have been released in Basilan. They were kidnapped while riding a pump-boat from their school to a major sea port in Zamboanga Sibugay province.