The US military said on Friday eight civilians likely were killed and three wounded in air strikes against Islamic State targets in Iraq and Syria between April 12 and July 4 last year.
It was only the third time since the start of the US-led air campaign against Islamic State in 2014 that the US military's Central Commander has disclosed civilian casualties following its internal investigations.
It has previously reported a total of six civilian deaths in its air campaign.
US military data shows there have been 9,627 US-led coalition air strikes as of Jan. 13, with 6,393 in Iraq and 3,234 in Syria.
"We continue to review additional claims of civilian casualties and will provide additional information in the future," Central Command said in a statement.
The latest eight civilian deaths occurred during five separate air strikes, including one on July 4 near al Raqqa, Islamic State's de facto capital in Syria.
The US military said it was targeting a "high-value individual" when a car and a motorcycle entered the target area after the weapon was released. Three unidentified civilians were likely killed, it said.
Strikes against Islamic State tactical units killed three civilians on June 11 near Soluk, Syria, and another two on April 12 near al Huwayjah, Iraq.
On June 19, a strike against two Islamic State vehicles near Tall al Adwaniyah, Syria, injured a civilian who appeared in the target area after the US aircraft released its weapon, the military said.
"In all of the cases released today, assessments determined that although the air strikes complied with the law of armed conflict and all appropriate precautions were taken, civilian casualties unfortunately did occur," it said.