Several hundred more Iraqi prisoners have been freed under a national reconciliation plan that Prime Minister Nouri al-Maliki announced on Sunday.
About 450 detainees left Tuesday the U.S.-run Abu Ghraib prison and other detention centers across Iraq.
Mr. Maliki has promised to release 2,500 prisoners by the end of the month. Officials say those being freed were not involved in violent crimes or were detained by mistake.
Meanwhile, the U.S. military says two insurgent attacks killed an American Marine and a soldier outside Baghdad Tuesday. And a car bomb in Kirkuk killed three Iraqis. Hours later, another car bomb killed three in Baghdad's Dora neighborhood.
In another development, Iraq's High Tribunal says the second trial of Saddam Hussein and several of his former top officials will start on August 21. They are charged with genocide and accused of killing tens of thousands of Kurds in the 1980s Anfal campaign.
The campaign to crush a Kurdish uprising also included the gassing in Halabja in 1988 that killed 5,000 people.
Saddam and seven co-defendants are currently on trial on charges they murdered 148 Shi'ites from the village of Dujail. The deaths followed an assassination attempt against the former Iraqi dictator in 1982.
Some information for this report was provided by AP and Reuters.