Militants ambushed and killed a convoy of Iraqi off-duty soldiers killing 10 and wounding 20, the country's military said.
Major Emad al-Dulaimi said on Monday that the attack took place the night before near the town of Rutba, in the sprawling western desert. He said the militants were armed with assault rifles and rockets.
It was not immediately clear who carried out the attack but al-Dulaimi blamed Islamic State.
IS has carried out many similar attacks targeting Iraqi forces in the past months to detract from the ongoing battle between Iraqi forces and IS militants in Mosul.
Rutba is about 240 miles west of Baghdad in the country's vast Anbar province. It is the last sizeable town on the way to the border with Jordan.