One of the most-wanted Malaysian militants who reportedly helped finance the ongoing siege of the southern Philippine city of Marawi by Islamist extremists is believed to have been killed in the fighting earlier this month.

Mahmud bin Ahmad was killed on 7 June in the clash between Filipino troops and local jihadis aligned with the Islamic State (Isis) group in the besieged city, the country's military chief said on Friday (23 June).

Mahmud was wounded in the fighting in Marawi last month and reportedly succumbed to his injuries suffered earlier this month, General Eduardo Ano told the Associated Press.

He is suspected to have channelised more than 30m Philippine pesos ($600,000) from Isis to the militants to acquire firearms, food and other supplies for the attack, Ano said citing intelligence shared by his foreign counterparts.

Ano further said that the Filipino troops have clues as to where Mahmud might be buried and that the military is trying to locate the exact spot with the help of civilians to confirm the intelligence they received.

Malaysian security forces too said they received information that Mahmud, a former Malaysian university professor, has died, and that they were trying to validate it, AP reported. They also confirmed that he was raising funds for the militants.

Mahmud reportedly received training in Afghanistan and appeared in a video that showed militant leaders planning the siege in Marawi, which is thought to be a sign that he playing a significant role in the unrest. The video was seized by Filipino troops from a militant hideout on 23 May.

The Philippines military chief said that a local militant leader, Omarkhayam Maute, is also believed to have been killed in the fighting in the early days of uprising. He, along with his brother Abdullah, reportedly formed the Maute group that supplied the bulk of the gunmen who stormed Marawi nearly a month ago.

Abdullah and Abu Sayyaf militant group's head Isnilon Hapilon are reported to be still fighting Filipino troops in Marawi, Ano added.

More than 250 gunmen, 58 soldiers and policemen and 26 civilians have died since the siege began last month. The siege in Marawi on the Philippines' Mindanao island is thought to be a serious attack in the Asia-Pacific region by the Islamist militants.

The siege began after militants began attacking the town and kidnapping civilians in retaliation for the army's failed raid to capture Hapilon. The clashes have displaced more than 200,000 residents of the city. More than 1,600 people have been rescued from the besieged area.

A view of the Maute group stronghold with an ISIS flag in Marawi City in southern Philippines.
A view of the Maute group stronghold with an ISIS flag in Marawi City in southern Philippines Reuters / Erik De Castro