Washington (CNN) -- The Treasury Department on Friday froze all U.S.-based financial assets of terror suspect Anwar al-Awlaki, who is being sought in Yemen for his alleged role as a planner of the failed bombing of a Detroit-bound passenger plane on Christmas Day last year.
Al-Awlaki, who was designated a "key leader" for the Yemen-based terror group al Qaeda in the Arabian Peninsula, "has sought to encourage his supporters to provide money for terrorist causes," Treasury Undersecretary Stuart Levey said in a statement.
He is an "extremely dangerous" individual who has "involved himself in every aspect of the supply chain of terrorism -- fundraising for terrorist groups, recruiting and training operatives, and planning and ordering attacks on innocents."
Levey said that "those who provide material support to [Awlaki] or [al Qaeda in the Arabian Peninsula] violate sanctions and expose themselves to serious consequences."
Al-Awlaki, Levey noted, was imprisoned in Yemen in 2006 on charges of kidnapping for ransom. He also was tied to an al Qaeda plot to kidnap an American official. He went into hiding in Yemen after being released from jail in 2007.
Recently, al-Awlaki purportedly wrote that a Seattle, Washington, cartoonist "should be taken as a prime target of assassination" for drawing a cartoon about the Prophet Mohammed.
CNN's Alan Silverleib contributed to this report.