The U.S. Defense Department says Iran continues to pose a major threat to Iraq's long-term stability.
In a report issued Tuesday to the U.S. Congress, the Pentagon said Iran's actions reflect a desire to oppose the development of a secure and stable Iraq - despite promises from Tehran to the contrary.
The report says Iran continues to host, train, fund, arm and direct militant groups intent on destabilizing Iraq.
Iran has dismissed earlier U.S. claims it is fostering unrest in Iraq.
The Pentagon report also accuses Iran of trying to derail a security agreement between the United States and Iraq that calls for the withdrawal of U.S. forces from Iraq by the end of 2011.
The report says Iran may use Iraq's provincial elections later this month to expand its influence in the country by supporting pro-Iranian candidates and political parties.
The United States and Iraq have long voiced concern that Iran is supporting militants fighting Iraqi and international forces in Iraq. Iran denies the charges.
Some information for this report was provided by AFPand Reuters.