An Iraqi security official says Kurdish forces have taken over parts of the country's largest dam, which was captured by the Islamic State extremist group earlier this month.

Gen. Tawfik Desty told The Associated Press that peshmerga forces backed by Iraqi and U.S. warplanes started the operation to retake Mosul Dam early Sunday.

Desty, a commander with the Kurdish forces at the dam, which was seized on Aug. 7, said they now control the eastern part of the dam and that fighting is still underway.

The U.S. launched airstrikes against the Islamic State group more than a week ago in a bid to halt its advance across the north. The extremists control vast swaths of Iraq and neighboring Syria.