MANILA - The Philippine military is checking reports that Malaysian terrorist Dr. Mahmud Ahmad was among 20 extremists killed after security forces attacked terrorist hideouts in Marawi City overnight.

The state assault killed 13 terrorists on late Wednesday and 7 more early Thursday, said Major General Restituto Padilla, spokesperson of the Armed Forces.

A mother and her teenage daughter, who were rescued during the operation, claimed that a foreigner resembling Dr. Mahmud was among the fatalities, said Padilla.

Intelligence operatives earlier said Mahmud was an alleged financier and recruiter that helped put together the coalition of pro-Islamic State fighters who stormed Marawi in May.

"Dahil hindi pa po natin nakukuha [ang bangkay], nakakapasok sa kinaroroonan ng mga kalaban, hindi pa po natin makumpirma ito 100 percent," Padilla told DZMM. "Pero tumataas po ang porsyento at nagiging kampante po kami, increasingly confident na ito na nga po iyun."

(We cannot fully confirm this because we have yet to retrieve the body from the terrorist hideout. But we are increasingly confident that the fatality was Mahmud.)

• READ: Military chasing Malaysian terrorist hiding in Marawi

A forensic examination is needed to confirm the "big possibility" that Mahmud was killed, said Colonel Romeo Brawner, deputy commander of Joint Task Group Ranao.

"There is a big possibility na kasama si Dr. Mahmud but we will only be definite once we have a match of probably DNA samples or maybe of the dental records and this has to be attested also by SOCO," Brawner said at a press conference.

Extremists are still putting up an "organized resistance" inside the battle zone, where some of the fatalities were killed from afar by government snipers, added Brawner.

The 39-year-old Mahmud, who holds a doctorate in religious studies and was a university lecturer in Kuala Lumpur, was the second-in-command of Abu Sayyaf leader Isnilon Hapilon, according to a July report by Indonesia-based Institute of Policy Analysis and Conflict (IPAC).

Mahmud took over the terrorist assault in Marawi after state troops on Monday neutralized Hapilon, the anointed "emir" of ISIS in Southeast Asia, and Omarkhayam Maute, one of 2 Middle East-educated brothers at the helm of the militant alliance, Armed Forces chief of staff Gen. Eduardo Año earlier said.

• READ: Malaysian teacher seen as new 'emir' of pro-IS militants

President Rodrigo Duterte on Tuesday announced the liberation of Marawi City, after more than 4 months of battling Islamic State-inspired terrorists. Marawi City Mayor Majul Usman Gandamra, however, said there are around 11 to 20 remaining terrorists in the city with more than 10 hostages.

• READ: Marawi mayor estimates 'total liberation' in 3 days

As of 6 a.m. Thursday, the battle for Marawi has left dead 882 rebels, 164 troops and 47 civilians. Some 1,772 hostages meanwhile have been rescued, said Brawner.

• IN PHOTOS: Marawi's 'liberation'

--With Dennis Datu, ABS-CBN News ; and Reuters