An air strike by the US-led coalition fighting the Islamic State may have killed Iraqi soldiers on Friday, the US military said, in what was likely the first "friendly fire" incident in the war on the extremists.

It appears to be the same incident which Iraq's joint operations command earlier said left 10 Iraqi soldiers killed or wounded south of the jihadist stronghold of Fallujah.

"Despite coordination with the Iraqi security forces on the ground, initial reports indicate the possibility one of the strikes resulted in the death of Iraqi soldiers," the US military said in a statement, adding that it would launch an investigation.

"The coalition offers condolences on the unfortunate loss of life of brave Iraq security forces on the front lines in the fight against Daesh today," it added, using an alternative acronym for the Islamic State group.

All coalition air strikes on the IS extremists are conducted with the approval of the Iraqi government, the US military said.

"To the best of our knowledge, there have been no previous incidents of friendly fire in Iraq involving the coalition during the course of Operation Inherent Resolve," it added.