Manila: Two key leaders of the May 23 attack in Marawi City were killed by government forces early Monday, reports say.

Isnilon Hapilon, leader of the Abu Sayyaf and Omarkhayam Maute, a senior leader of the clan-led, Central Mindanao-based Maute, were killed in a dawn attack mounted by elite units of the Philippine military, sources said.

A photo, believed to be that of the dead Hapilon and Omarkhayam Maute made rounds in social networking sites on Monday morning.

Defence Secretary Delfin Lorenzana confirmed the death of the two in an official statement.

“We have received information from Armed Forces of the Philippines ground commanders in Marawi City that the operation conducted to retake the last remaining Daesh-Maute stronghold has resulted in the death of the last terrorist leaders Isnilon Hapilon and Omar Maute and that their bodies were recovered by our operating units,” he said.

“The report also said that our troops have rescued 17 civilian hostages and mopping up operations are underway,” he said.

The two believed to be key personalities in activities by the Daesh-inspired Abu Sayyaf-Maute nexus that aims to establish an Islamic caliphate in Southeast Asia with Marawi City as the centre.

They had been seen in a video that surfaced in social networking sites after the May 23 attack, while planning the execution and conduct of the incident in Marawi City.

The main battle area had shrunk to five hectare area with only about 150 buildings and structures need to be cleared.

More than 802 members of the Maute-Abu Sayyaf, joined by a number of foreign volunteers, were killed in the four months of fighting while government forces who died in combat number 160.

The number of rescued hostages are at 1,770, and those still held in captivity are about three dozen more.

Hapilon has a $5 million (Dh18.3 million) bounty offered by the US Department of State under its Rewards for Justice Programme.

“Isnilon Hapilon is a senior leader of the Abu Sayyaf Group, a foreign terrorist organisation operating in the southern Philippines. The group and its leadership are integrated with the worldwide network [of Islamist militants], including Jemaah Islamiyah and Al Qaida,” the US State Department said.

Hapilon was indicted in the District of Columbia for his alleged involvement in terrorist acts against US nationals and other foreign nationals in and around the Republic of the Philippines.

The United States as well as Australia had fielded unarmed aircraft and had been carrying out electronic surveillance in the battle area as part of their contribution in the fight against terrorism in Marawi City.