MANILA (UPDATED) - A severed head found Monday near the Jolo Cathedral in Jolo, Sulu "likely" belongs to Robert Hall, a Canadian captive of the Abu Sayyaf Group (ASG), according to an official of the Armed Forces of the Philippines (AFP).

AFP Western Mindanao Command spokesperson Major Filemon Tan Jr. said Tuesday that the head appears to be that of a Caucasian male and bears a close resemblance to Hall.

"Malamang po, malamang. Malaki po ang probability na ito na si Robert Hall," Tan told radio dzMM.

However, the Army official stressed that Scene of the Crime Operatives (SOCO) still need to conduct a DNA test on the head before Philippine authorities can confirm that the head belongs to Hall.

"Bagama't nakikita po natin na ang features niya ay kay Robert Hall, hindi po natin pwedeng i-declare iyan hanggang hindi dumaan sa proseso, sa DNA testing na lahat po ay gagawin ng PNP SOCO before they can formally confirm na iyan po talaga ang ulo ni Robert Hall," Tan said.

Canadian Prime Minister Justin Trudeau earlier said the Canadian government has "reason to believe" that Hall has been killed by his Filipino captors.

Hall was taken captive with three other people by Abu Sayyaf militants in September 2015 from an upscale resort on Samal island, hundreds of miles east of Jolo.

The bandits initially demanded P1 billion each for the detainees, but it lowered the ransom to P300 million each early this year. Both the Philippine and Canadian government, however, reiterated a policy against paying ransom in these cases.

Intelligence reports said Hall was executed some 15 minutes after the 3 p.m. ransom deadline on Monday in the mountains outside the island's Patikul town.

Tan said authorities were still searching for the foreigner's body.

Abu Sayyaf executed Canadian John Ridsdel, a former mining executive, in April. A Norwegian man and a Filipino woman are still held captive.

READ: Canadian hostage's tropical retirement dream ends in cold blood

MILITARY COUNTER-ATTACK

Tan said the Army is still sustaining military operations to rescue the other hostages.

The official said counter-terrorist operations have gained ground but admitted that Sulu's terrain, marked by numerous entry points and a vast shoreline, have blocked the Army's progress.

"There are many variables pagdating sa operational area. Isa po doon ay iyung terrain. Karamihan po ng mga Abu Sayyaf ay locals diyan sa Sulu. Alam po nila ang pasikot-sikot, that is one consideration na kailangan natin ibalanse," he explained.

He added that police face manpower contraints in guarding police checkpoints across the island.

Tan also said some local residents who are related to ASG fighters would often inform the militants about the location of authorities.

He urged the public to refrain from condoning the illegal activities of the militants.

"Sila po mismo ang dapat magtakwil. They should make the community inhospitable for these terrorists," he said.

The Army official also maintained government's policy of not paying ransom for the release of hostages."We have no business in talking to these bandits especially pagdating sa ransom. We adhere to the no-ransom policy," he said.

Abu Sayyaf, based in the south of the mainly Catholic country, is known for kidnapping, beheadings and extortion.

READ: Five things to know about the Abu Sayyaf

Security is precarious in the southern Philippines despite a 2014 peace pact between the government and the largest Muslim rebel group that ended 45 years of conflict. -- With a report from Reuters