The United States imposed sanctions on Tuesday on a Taliban leader and fundraiser who it said helped plan military attacks in Afghanistan, authorize the assassination of Afghan government leaders and raise millions of dollars for the Taliban.

Torek Agha was named a "Specially Designated Global Terrorist" by the Treasury Department, an action that allows the U.S. government to freeze property or interest in property under American jurisdiction. It also prohibits transactions by Americans involving Agha, the Treasury Department said in a statement.

"Torek Agha, a longstanding Taliban member, has been central to spearheading brutal military attacks and raising millions of dollars to support the Taliban's ruthless acts of terrorism," said Adam Szubin, acting under secretary for terrorism and financial intelligence.

Agha serves on a leadership panel that oversaw Taliban activities in southern and western Afghanistan, the Treasury Department said. He was a key commander and member of the Taliban's military council and of another group responsible for strategic planning and logistics operations, it said.

"He was one of four senior Taliban commanders who, as of early 2012, had authorized the use of an unidentified chemical powder to assassinate senior Afghan government officials," the department said.

The department said Agha was a "prolific fundraiser" who has brought millions of dollars from the Gulf to the Taliban. He collected $4 million from Gulf donors in 2010 and $2 million in 2009, it said.

(Reporting by Doina Chiacu; Editing by Will Dunham)