President Rodrigo Duterte said last night a top Malaysian militant tipped to become the point man of the Islamic State in Iraq and Syria (ISIS) terror group in South-east Asia was killed in overnight skirmishes in Marawi city.
"He was taken this afternoon," said Mr Duterte, of Mahmud Ahmad, 41, a former lecturer at Universiti Malaya.
"That completes the story," he added, referring to two other top militants, Isnilon Hapilon and Omarkhayam Maute, who were killed on Monday.
The duo, who plotted and led the attack on Marawi on May 23 with Mahmud, were killed by security forces. Military spokesman Restituto Padilla was quoted by the Philippine Daily Inquirer as confirming Mahmud's death.
"Hostages rescued know who he was and reported he was killed last night," he said.
He later told Agence France-Presse that a DNA test would be conducted on Mahmud's body.
Colonel Romeo Brawner, deputy commander of Joint Task Force Ranao, told reporters earlier in the day there was a "big possibility" Mahmud was among 20 gunmen killed in the latest fighting in Marawi.
The conflict began when hundreds of militants stormed Marawi in May and held parts of it for months, in an audacious bid to turn the city into a "province" of ISIS.
More than 1,000 militants, government troops and civilians have been killed in the conflict.
Half of Marawi lies in ruins, levelled by air raids, artillery barrages and fierce urban fighting. About 400,000 have been displaced.
Some experts believe Mahmud may have already taken the helm of ISIS' South-east Asia wing, following the death on Monday of its Filipino leader Hapilon.
Mahmud, with help from Bahrumsyah, head of an ISIS combat unit in Syria, raised funds and recruited fighters for the attack on Marawi, according to the Jakarta-based Institute for Policy Analysis of Conflict.
Security expert Rommel Banlaoi, director of the Centre for Intelligence and National Security Studies, said Mahmud's death "would not mean the end of the ISIS threat in the Philippines because there are other high-value terrorists still active in Mindanao, not to mention foreign fighters from Indonesia and other parts of the world".
Dr Banlaoi agreed with the military's assessment that Mahmud "doesn't have a good track record when it comes to combat ability".
He cited Sabahan Mohammad Amin Baco, 31, and Malaysian municipal council worker Muhammad Joraimee Awang Raimee, 42, as bigger threats because of their combat experience and bomb-making skills.
Security forces in southern Mindanao island and in Manila were on high alert to pre-empt attacks by die-hard militants seeking revenge for the deaths of their leaders.
Major-General Padilla said Hapilon's and Mahmud's sympathisers could lay siege to another city or harass far-flung villages in Mindanao.