Abu Sayyaf, al Qaeda-linked Muslim extremists fighting for an independent Islamic state in the southern Philippines, beheaded two men abducted from the remote southern island of Jolo in August.

The latest kidnappings are the first carried out by the group since some 1,200 American troops arrived in the area in January to aid a military offensive against the militants.

In June, Philippine troops trained by U.S. advisors stormed an Abu Sayyaf jungle camp in an effort to rescue three hostages. Although two were killed in the rescue attempt, the other hostage, a U.S. missionary, escaped with only minor injuries.

Since then the Philippine government, led by President Gloria Macapagal Arroyo, has vowed an all-out effort to crush the Abu Sayyaf.