US Defense Secretary Ash Carter said Saturday that the US airstrike that may have killed a number of Iraqi soldiers on Friday seems to be "a mistake that involved both sides."

He called Iraqi Prime Minister Haider al-Abadi to express condolences, the CBSNews reported.

Speaking to reporters during a visit to the USS Kearsarge in the Gulf area, Carter said the incident near the western Iraqi city of Fallujah was "regrettable."

"These kinds of things happen when you're fighting side by side as we are," Carter said. He said the airstrike Friday "has all the indications of being a mistake of the kind that can happen on a dynamic battlefield."

Carter, who spent two days in Iraq this past week, called Abadi from the USS Kearsarge, an amphibious assault ship supporting coalition missions in Iraq and Syria against militants with the Daesh of Iraq and Syria. The Kearsarge carries a Marine expeditionary unit and naval aircraft.

The Pentagon chief did not provide details about the airstrike, which the US military headquarters in charge of the war effort in Syria and Iraq said was one of several it conducted Friday against Daesh targets.

A US military statement said the airstrikes came in response to requests and information provided by Iraqi security forces on the ground near Fallujah, which is in Daesh control, and were done in coordination with Iraqi forces.

A senior US defense official said that although an investigation was in its early stages the incident was likely due to the "fog of war" and actual fog. The official indicated that bad weather could have been a factor in the incident.

Carter said he told Abadi that the US was investigating and would work with the Iraqis.

Source: MENA