US air strikes have killed a leader of the Islamic State in the Iraqi city of Fallujah as US and Iraqi government forces continue a sustained attack to defeat terrorist networks.

Maher al-Bilawi, the commander of Daesh forces in Falluajh, was killed on 25 May, according to the spokesperson of the US military campaign leading the fight against ISIS in Iraq and Syria.

Operation Inherent Resolve army colonel Steve Warren confirmed the death of Mr al-Bilawi and more than 70 terrorists in recent air strikes when he spoke to the press from a live conference in Baghdad.

He did not specify where the strike took place, how long Mr al-Bilawi had been in the city or how the army came to know the whereabouts of the ISIS leader. 

The news comes five days after several news outlets reported that a local official said that airstrikes had killed the so-called “Wilayah Fallujah”, Mr al-Bilawi, on 22 May, east of the city of Ramadi.

Mr Warren said that news was "incorrect" and the killing two days ago was part of the coalition's plan to “constantly chip away” at the terrorist network.

“This won’t cause the enemy to stop fighting but it’s a blow and it creates confusion and the leadership has to move around,” he said.

The air strikes are an attempt to “liberate” the city, said Mr Warren, which is home to around 150,000 citizens.

The Iraqi government has dropped leaflets on the city, asking them to leave or mark their houses via white sheets, while the government works on evacuation routes.

Mr Warren acknowledged that ISIS “most likely” will also be holding out white sheets to hide behind civilians, and that was “part of the complexity of human warfare”.

In the last 24 days there have been 20 air strikes across Iraq and Syria, which amounted to the deaths of at least 70 terrorists.

“We are still early in the Fallujah fight so it’s unclear how long this battle will last,” said Mr Warren during his last press briefing. He will be soon replaced by Colonel Chris Garver.

The US forces’  goal is to also liberate the Iraqi city of Mosul, and Mr Warren said different forces will be employed there and in Fallujah.

“We are going to every city sooner or later,” he said. “It’s just a case of sequencing.”