The release of prisoners is seen as a central feature of Prime Minister Nuri al-Maliki's national reconciliation plan.
The Justice Ministry says some 3,000 prisoners have been freed since the plan was launched on June 6.
In other news, the U.S. military says three American soldiers were killed by "enemy action" on July 8 in Iraq's western Al-Anbar Province. No further details were released.
Overall, a total of five U.S. soldiers have been reported killed in Iraq since the beginning of July.
(AP, AFP, Reuters)