After acting on information from Iraqi security forces on the ground near Fallujah, coalition forces conducted several air strikes against Islamic State and "initial reports indicate the possibility one of the strikes resulted in the death of Iraqi soldiers," the US military said in a statement.
"We will conduct a thorough investigation to determine the facts," it continued. "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."
Just hours earlier, the Pentagon denied Iraqi reports that a US air strike killed at least one soldier and injured others.
An unverified video of the alleged attack was obtained from a local source in Iraq by RT's Ruptly video agency.
According to Hakim al-Zamili, the head of Iraqi parliament's Security and Defense Committee, 30 soldiers from the Iraqi army's 55 brigade were killed and 20 were injured in a US air strike on the town of al-Naimiya in the al-Fallujah province.
Initially, US Defense Department spokesman Major Roger Cabiness said Zamili's claim was "not true."
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According to the Iraqi army's command center in Baghdad, the strike was requested by Iraqi troops on the ground. The attack was launched without an update on the location of the ground troops, the command center said, and bad weather prevented air support from differentiating between Iraqi soldiers and enemy forces.
One Iraqi commander was killed in the strike and nine others were injured, according to the command center.