WASHINGTON - The Pentagon said on Monday a US-led coalition airstrike had killed a senior military leader of the Islamic State (IS) in Iraq.

"On May 6th, a coalition airstrike targeted Abu Waheeb, ISIL's military emir for Anbar Province and a former member of al-Qaeda in Iraq who has appeared in ISIL execution videos," said Pentagon spokesman Peter Cook here at a briefing, referring to another acronym of the group.

The strike was successful and three other IS fighters were killed, Cook added.

"We think this is a significant member of the leadership team (of IS), particularly in a critical area (of Anbar province)," said Cook.

Iraqi troops and allied militias have been fighting for months to retake control of key cities and towns in Anbar, Iraq's largest province, from IS militants, who previously seized most of Anbar and tried to advance toward Baghdad.