Warplanes attacked the militants of the so-called Islamic State of Iraq and the Levant as they appeared to be parading near Fallujah, a city that has been under the control of the terrorists since January.
One of the ISIL leaders, identified as Yasser Nayi, was among those killed in the airstrike, the army said.
About 400 militants hid in a four-story building in Fallujah when they saw the warplanes approaching, an army commander in the city told the official Iraquiya network.
Military aircraft fired rockets and machine guns at the building, killing about 270 Islamic extremists and destroying seven vehicles, officials said.
Airstrikes also killed about 70 militants in the city of Samarra and 17 others in Baquba, the capital of Diyala province, state television reported.
A total of 56 terrorists were killed in a series of operations in Baghdad in the past 24 hours, the armed forces said.
The army killed 279 militants over the weekend in fighting in Saladin, Diyala and Nineveh provinces, armed forces spokesman Maj. Gen. Qassim Atta said on Sunday.
The ISIL terrorists are holding Mosul, Iraq's second-largest city and the capital of Nineveh, and threatening to advance on Baghdad.
BA/BA