President Bush has signed an order that allows the U.S. government to block the assets of any person or group that threatens the stability of Iraq.
The order exempts the United States.
White House spokesman Tony Snow says the order targets terrorist and insurgent groups, including those supported by Syria and Iran, that are not covered by existing measures.
Mr. Bush's action allows the U.S. Treasury and other agencies to freeze the property and assets in the United States of people or entities deemed to be working to destabilize Iraq or undermine reconstruction or humanitarian efforts.
No person or entity was designated under the order when it was announced Tuesday.
Some information for this report was provided by AFP, AP and Reuters.