The U.S. military says at least 352 civilians have been killed by coalition air strikes in Iraq and Syria since the beginning of the air campaign targeting Islamic State (IS) forces in 2014.

The figure released by the Pentagon in an April 30 statement is far lower than tallies compiled by independent groups.

The monitoring group Airwars says the air strikes have killed more than 3,000 civilians.

"We regret the unintentional loss of civilian lives…and express our deepest sympathies to the families and others affected by these strikes," the Pentagon said in the statement.

It added that in each case "all feasible precautions were taken," but that the strikes nonetheless resulted in the "unintentional" deaths of civilians.

The United States launched its air campaign targeting IS forces in August 2014 after the extremist group overran large swaths of the Iraq, including its second-largest city, Mosul.

Based on reporting by AP and Reuters