An airstrike on Islamist militants holed up in the southern Philippine city of Marawi mistakenly killed two soldiers and wounded 11 others on Wednesday, a military spokesman said.

This has been the second accident involving a military aircraft hitting soldiers on the ground since the conflict in Marawi started in May.

The air force's public affairs chief Col. Edgard Arevalo said in a statement that a military bomber missed its target during an airstrike around noontime Wednesday and the ordnance hit buildings near the soldiers' position.

Citing initial report from ground commanders in Marawi City, Arevalo said "the bomb was 250 meters off target."

"The impact of the explosion caused the collapse of nearby structures. Large debris from heavily reinforced buildings accidentally hit the two of our personnel who succumbed to death in the process," he said.

Arevalo said the 11 wounded "are ambulatory" and are recuperating in the hospital.

He said the military is "saddened by this unfortunate incident," the second accident involving a military aircraft hitting soldiers on the ground.

On May 31, a rocket bomb fired by an SF-260 plane conducting an airstrike also accidentally hit troops on ground, killing 10 soldiers and wounded seven others.

More than 500 people have so far been killed in the 51-day war to defeat the militants allied with the Islamic State (IS) that occupied Marawi City.

Before the latest report came in, Arevalo said the number of casualty in the ongoing Marawi conflict has reached 518, including 389 extremists, 90 security forces and 39 civilians.

Meanwhile, the battle to retake the city continues.

President Rodrigo Duterte has expressed hope that the conflict will end in 10 to 15 days.

source: Xinhua