Tom Vanden Brook, and John Bacon

USA TODAY

The U.S.-led coalition fighting the Islamic State said Tuesday it could not confirm reports that Islamic State leader Abu Bakr al-Baghdadi had been killed in a U.S. airstrike.

Army Col. Chris Garver, the top spokesman for the coalition in Iraq, told USA TODAY he was aware of the reports from the Islamic news agency AlhlulBayt and other sources. Garver said that, if true, al-Baghdadi's death would be welcome news but would not signal the end of the fight against the terrorist group.

AlhlulBayt reported the militant leader was killed Sunday in an airstrike in the Raqqa, Syria, the Islamic State's de facto capital.

Previous reports claiming al-Baghdadi, 44, was killed or wounded have surfaced since he proclaimed himself the caliph, or supreme religious leader, of all Muslims two years ago. Last week an Iraqi TV station claimed he was wounded in an airstrike, a report that was never confirmed.

Similar reports circulated in October 2015 and November 2014.

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An Iraqi-born Sunni Muslim, al-Baghdadi was arrested by U.S. forces in 2004 near Fallujah. He was detained for several months before being released as a "low-level" prisoner. The U.S. designated al-Baghdadi a terrorist four years ago, authorizing a $10 million reward for information leading to his death or capture.

The Islamic State's No. 2 leader, Ahmad al-Hayali, reportedly was killed by a U.S. airstrike last summer, U.S. officials have said. He was succeeded by Abu Fatima al-Jaheishi.

​The Islamic State took control of a large swath of Iraq and Syria, but lost some ground in recent months. The battlefield struggles come as jihadist "lone wolf" attacks such as those in San Bernardino, Calif., and Orlando flourish.

Dominated by Sunni Arabs from Syria and Iraq, the group claims religious, political and military authority over Muslims worldwide as it attempts to build a state ruled by strict sharia law.