Smoke rises from Islamic State positions Nov. 14, 2015, during a U.S.-led coalition airstrike in support of an offensive by Iraqi forces to regain control of the western suburbs of the city of Ramadi. (Osama Sami/AP)

The Iraqi military said an airstrike by the U.S.-led coalition hit its forces Friday, the first time it has reported a friendly-fire incident since American jets began bombing Islamic State militants in the country last year.

The strike took place as the Iraqi army engaged in close combat with the militants in poor weather conditions south of the city of Fallujah, about 40 miles west of Baghdad, the Iraqi Defense Ministry said in a statement. One soldier was killed, and nine were injured, it said.

But soldiers said the death toll was higher. One officer injured in the strike, who spoke on the condition of anonymity because he was not authorized to speak to the news media, said 25 soldiers were killed and 37 were wounded. A military medic said he had treated at least 20 injured soldiers.

The U.S.-led coalition said it had launched an investigation and offered condolences to the Iraqi security forces. In a statement, it confirmed that coalition planes had conducted several airstrikes in the area.

“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,” it said.

Army Col. Steve Warren, a U.S. military spokesman in Baghdad, said the reported strike is under investigation. “We don’t know at this point,” Warren said, adding that flight logs are being checked to see whether coalition aircraft were in the area.

The errant airstrike could complicate political discussions in Baghdad as the United States offers greater support for Iraqi forces in their ongoing offensives against the Islamic State. During a visit to Baghdad this week, Defense Secretary Ashton B. Carter said the Iraqi government had not yet taken up a U.S. offer to provide close air support with Apache helicopters for the campaign to wrest control of the western city of Ramadi from Islamic State fighters.

Iraqi forces have been heavily reliant on U.S. air support as they retake territory from the Islamic State. But the government also faces pressure from neighboring Iran, a U.S. adversary and Iraq’s other main military ally, and from the Iraqi Shiite militias that Iran backs.

At Yarmouk Hospital in Baghdad, chaotic scenes unfolded as the injured were brought in on stretchers. Soldiers and family members crammed the entrance and hallways.

“At first, we thought it was something fired by Daesh,” said one army soldier, his uniform bloodstained from carrying the injured. Daesh is an Arabic term for the Islamic State. “The explosion was very big. We ran. I saw many dead bodies. I saw that one of my friends had lost a leg.”

In its statement, the Iraqi military said it requested air support from the U.S.-led coalition near the town of Amiriyat al-Fallujah on Friday because the weather prevented Iraqi planes from providing assistance.

“The coalition launched two airstrikes which caused many casualties in the ranks of the enemy,” the statement said. Iraqi forces then moved forward rapidly, it said.

“The distance between our forces and the enemy was very close, meters,” the statement continued. “Our forces got mixed.”

In a third strike, “because they couldn’t distinguish from the air” between the forces on the ground, “there were some casualties among our forces, too,” the Iraqi statement said.

Brig. Gen. Yahya Rasoul, a spokesman for the Iraqi military, said he did not know which coalition planes were involved.

In addition to contesting the death toll, the injured officer also disputed the official version of events.

“We were moving forward and Daesh were retreating, when suddenly the bombing took place on the forces that were behind us,” he said. “It was meant to be a secure area.”

The fact that senior officers were injured showed that it was not front-line troops that were hit, he said, adding that the weather conditions were not particularly bad.

“I heard a loud explosion, and then after that, I couldn’t hear anything,” he continued. “All I could see was dust, and then I passed out.”

The army medic said that he did not know how many soldiers had been killed but that far more than nine were injured.

“I treated at least 20 injured, and my colleagues treated more,” he said, also on the condition of anonymity because he was not authorized to speak to the news media.

The report is likely to provide fresh material for critics of U.S. military assistance in Iraq, where conspiracy theories that the United States is supporting the Islamic State, rather than fighting it, are widespread.

Hakim al-Zamili, the head of the Iraqi parliament’s defense and security committee, said that more than 20 soldiers were killed in the airstrike and that 30 were injured. Zamili, a Shiite militia commander, has repeatedly accused the United States of friendly-fire incidents and of dropping weapons to Islamic State militants in the past. He called for an investigation.

“The army is on the ground fighting Daesh, and the Americans are bombing them,” said Ali al-Maliki, who was at the hospital visiting his injured 23-year-old brother. “Now people will believe that Daesh was made by the Americans, because when the Iraqi army was moving forward to take their territory, they bombed [the army].”

The coalition statement said Iraq had been formally invited to participate in the investigation. “We take great measures to prevent these types of incident while protecting our partner forces,” it said, adding that all strikes were conducted at the request of the Iraqi government. “We are fully committed to the safety of our Iraqi partners while pursuing the destruction of our mutual enemies.”

Dan Lamothe in Washington contributed to this report.

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