"They crush them with their vehicles and kill them just on suspicion," he said. "This is completely unacceptable." Attacks on civilians will play a role in future decisions on how long to ask American forces to remain in Iraq, the prime minister added.

The denunciation was an unusual declaration for a government that remains desperately dependent on American forces to keep some form of order in the country amid a resilient Sunni Arab insurgency in the west, widespread sectarian violence in Baghdad, and deadly feuding among Shiite militias that increasingly control the south.