Four anti-al-Qaida fighters died Sunday when two roadside bombs exploded as their patrol passed by, Iraqi police and health officials said.
A police officer said the first bomb went off next to a passing patrol of the Sahwa or Awakening Councils, a network of predominantly Sunni Arab militias allied with the Iraqi government.
The officer said the second bomb hit another patrol rushing to the scene a few minutes later, killing two others. Three Sahwa fighters were injured in the blasts.
The attack took place near the town of Mishahda, 20 miles (30 kilometers) north of Baghdad.
A doctor in a nearby hospital confirmed the casualty figures.
Both officials spoke on condition of anonymity as they were not authorized to release information.
Many of the Sahwa were former insurgents or sympathizers who later turned on more extreme groups such as al-Qaida in one of the key turning points of the war. Since then, the Sahwa have often been targeted by insurgents who accuse them of being traitors and supporters of the Shiite-led government in Baghdad.
Meanwhile, Iraqi Prime Minister Nouri al-Maliki and President Jalal Talabani announced Sunday that the main Iraqi political blocs will meet Tuesday evening to discuss the American military withdrawal from Iraq and whether they would like to request a small American military force stay in the country after Dec. 31.
All U.S. troops are to leave the country by the end of this year under a security agreement between Iraq and the U.S. signed in 2008.
U.S. officials, speaking on condition of anonymity because they were discussing internal deliberations, have said the Obama administration is proposing a force of between 3,000 and 5,000 troops in order to train Iraqi security forces.
Iraqi political leaders have indicated they would like to have some American presence in the country after Dec. 31 to help their still-nascent security forces, but have so far been unable to agree on how many troops should stay and what they would like them to do.
Iraqi political leaders announced in August that they would be opening talks with the U.S. on whether to have a residual training force but there has been almost no progress since then.
Associated Press writer Rebecca Santana contributed to this report.