The attack targeted government-backed Sunni militia members lining up to be paid in the town of Radwaniya.

The Sunni militia fighters, known as the Sahwa or Awakening Councils, were once allied with al-Qaeda, but turned against the militant group in 2006.

"There were more than 85 people lined up in three lines at the main gate of the military base to receive salaries when a person approached us," said a survivor, 20-year-old Tayseer Mehsen.

In a second attack on the same day, a suicide bomber killed at least three people and wounded six at a meeting of Sunni militia leaders in western Iraq, police said.