The pre-dawn attack on the Marine outpost in the strife-torn island of Jolo left two soldiers dead and five wounded while the bodies of three gunmen were recovered later, Lieutenant Colonel Randolph Cabangbang said.

The military was still checking which of the many armed groups on Jolo island might be behind this attack.

"Everyone in this island has a gun. It is not automatic that armed men are rebels or terrorists," Cabangbang told AFP.

extremist group founded with the help of the Al-Qaeda network in the 1990s.

The Abu Sayyaf has been linked to the worst terror attacks in Philippine history, including a ferry bombing that killed more than 100 people in 2004.

But Cabangbang said the Abu Sayyaf did not usually attack heavily-armed military outposts and preferred to stage kidnappings for ransom, and bombings.

Aside from the Abu Sayyaf, the other armed groups in Jolo include bandits, former rebels and the private armed bands of powerful political clans.