Islamist militants have beheaded a hostage in the southern Philippines after no ransom was paid for his release, a regional military spokesperson said today.

The severed head of the Filipino victim, identified as Patrick Jhames Almodavar, was found yesterday in a village on Jolo Island, 1,000km south of Manila, Major Filemon Tan said.

The head was wrapped in a plastic bag and left alongside a road, Tan said.

Almodavar was abducted by members of the Abu Sayyaf terrorist group on July 16 in the town of Jolo, and the kidnappers were demanding 1 million pesos (about US$22,000) as a ransom.

Last week, the militants released a video of Almodavar appealing for help.

Abu Sayyaf, which has been blamed for some of the deadliest terrorist attacks in the Philippines, beheaded two Canadian hostages in April and June after no ransom was paid.

The militants are also suspected of holding others captive on Jolo Island including five Malaysians, a Norwegian, a Dutchman and several Filipinos.

President Rodrigo Duterte has directed the military to crush Abu Sayyaf and also warned that the group could be a source of recruitment for the Islamic State extremist group.

- dpa