MANILA - The military on Friday said there was a "strong indication" that Omar Maute, one of the two brothers who founded the terrorist group behind attacks in Marawi City, is already dead.

The report of Maute's possible death first reached the military two weeks ago, Lt. Col. Jo-ar Herrera, spokesperson of Joint Task Force Marawi, said in a press conference in Marawi City.

JTF Marawi: There is a strong indication that Omar Maute has already been killed in a firefight two weeks ago. pic.twitter.com/P9ZCb1zo7U

— Ron Gagalac (@rongagalac) June 23, 2017

Maute was possibly killed during an encounter in an area considered as the Maute group's lair in the Islamic City, but government troops have yet to extract his body from the war zone, Herrera said.

Once confirmed, his death may be considered a blow to the Islamic State-linked terror group amid continuing government offensives a month into the siege.

The Maute brothers were among terror leaders known to have plotted attacks in Marawi last month, just before firefights erupted on May 23.

With Maute likely gone, his brother Abdullah may be the one now leading the group's operations, the military said.

Earlier this month, the brothers' parents- father Cayamora and mother Farhana- were arrested in separate police operations.

Meanwhile, Isnilon Hapilon, said to be the anointed ISIS leader in Southeast Asia, is also still alive and helping Abdullah lead the rebels, the military said.

Malacañang earlier announced a P5 million bounty for the "neutralization" of each of the Maute brothers, and another P10 million for Hapilon.

Speaking to reporters in Manila on Thursday, Armed Forces of the Philippines Chief of Staff Eduardo Año also shared the information.

"Hapilon is still inside (Marawi), kaya nga siguro defying 'yung mga members nito, because Hapilon is still alive. But si Omar Maute, more or less mukhang patay na talaga itong si Omar Maute. Abdullah is still alive, still there, still inside Marawi," he said.

• READ: Omar Maute likely dead, AFP chief says

News of Omar's possible death came a month since clashes began, prompting President Rodrigo Duterte to place the entire Mindanao under martial law.

As of 6 p.m. Thursday, government placed the death toll at 375, among them 280 terror suspects, 69 government troops and 26 civilians. -- with reports from Ron Gagalac and Edwin Sevidal, ABS-CBN News