The U.S. government on Friday designated groups associated with the Iranian-based Mujahedin-e Khalq (search) as foreign terrorist organizations, shutting down political offices and cutting off finances.

Secretary of State Colin Powell added the Mujahedin-e Khalq's parent and sister organizations to the list of foreign terrorist organizations. The designation of the National Council of Resistance of Iran (search) and People’s Mujahedin of Iran (search) as FTOs means that the U.S. government can impose sanctions against individuals and organizations that "associate" with the blacklisted groups.

The designation was "based on information from a variety of sources that those entities functioned as part of the MEK and have supported the MEK's acts of terrorism," State Department spokesman Tom Casey said in a statement released Friday.

The Treasury Department's Office of Foreign Assets Control also declared the NCRI under all of its aliases "including its U.S. press office" to be a "Specially Designated Global Terrorist" group.

The State Department maintains a list of foreign terrorist organizations that it uses to pressure countries to dissolve. FTO designations are valid for two years, after which they must be redesignated or they automatically expire. U.S. citizens are banned from supporting FTOs.

MEK is listed on the State Department’s official list of terrorist organizations, and has been blamed for supporting the U.S. embassy takeover and overthrow of the Shah in 1979. The group was first named a terrorist organization in 1997.

In June, Alireza Jafarzadeh, chief congressional liaison and spokesman for NCRI, said NCRI seeks to overthrow the Islamic regime and replace it with a government that espouses political pluralism, fair and open elections, equality, free markets and separation of religion and state.

He also defended MEK to Foxnews.com, saying it has never targeted American interests or asked for financial aid from Washington, and it had offered critical intelligence to the U.S. government, providing information on two nuclear bomb-making facilities in Iran previously unknown to U.S. officials.