Authorities in the southern Philippines say 13 suspected Muslim militants and two soldiers were killed Sunday in a clash between members of a little-known rebel group and government troops on Jolo island.

A military spokesman, Lieutenant Colonel Randolph Cabangbang, said about 50 young gunmen attacked the Marine outpost in Sulu province, triggering a two-hour battle. He said troops later recovered 13 of the assailants' bodies along with several firearms. At least five marines were wounded in the clash.

Cabangbang tied the pre-dawn attack to a radical organization “Awliyah” with ties to the al-Qaida-linked Abu Sayyaf militant group.

Abu Sayyaf, long active in the southern Philippines, first appeared in the 1990s and is considered a terrorist organization by Washington and Manila. It is accused of carrying out some of the worst terrorist attacks in recent Philippine history.

The group, which uses kidnappings and extortion to raise money, claimed responsibility for the 2004 bombing of a ferry near Manila Bay that killed more than 100 people. The group is thought to have fewer than 400 members.