|The United States has offered a reward of up to $5 million for information about Mehsud [EPA]
US prosecutors have charged Hakimullah Mehsud, the leader of the Pakistani Taliban, with organising an attack that killed seven CIA employees at an American base in Afghanistan last December.
The US Justice department said on Wednesday that Mehsud, believed to be in the tribal areas of Pakistan, was charged with conspiracy to kill Americans overseas and to use a weapon of mass destruction.
"Criminal charges are meant to deal with Hakimullah if he's captured," a US official told Reuters news agency.
"He can face justice in other ways, too. That hasn't changed."
The attack on the CIA on December 30 is considered to be the second deadliest in the organisation's history.
US military forces have attempted to assassinate Mehsud numerous times using unmanned aerial drones, and the US state department is offering a reward of up to $5 million for information about his whereabouts.
The United States also formally added the Pakistani Taliban to its list of so-called foreign terrorist organisations on Wednesday, imposing financial and travel sanctions on the group, which claimed responsibility for a failed bombing in New York's Times Square in May.
Mehsud is the head of the group known as Tehrik-e-Taliban Pakistan (TTP), or Taliban Movement of Pakistan.
Hillary Clinton, the US secretary of state, said in a statement that the TTP met the criteria to be included on the list, which bars any material support to and freezes the financial assets of groups deemed involved in terrorism.
The TTP was formed in December 2007 as an alliance of Pakistani armed groups to attack the Pakistani state. It believes the government is illegitimate because it is helping the US-led war in neighbouring Afghanistan.
The TTP hit the US headlines following the Times Square bomb attempt, which saw a naturalised US citizen of Pakistani origin arrested after a sport utility vehicle rigged with a crude explosive device that included firecrackers and propane gas tanks was found in New York's main tourist hub.
Faisal Shahzad, the alleged attempted bomber, later pleaded guilty and said he had received bomb-making training and $12,000 from the TTP in Pakistan to facilitate the bomb attempt.
US officials have praised Pakistan's efforts against armed groups, but Clinton ruffled some feathers when she told the CBS television network that Pakistan would face "severe consequences" if a successful attack in the United States were traced to Pakistan.
There are 46 groups on the US list of "foreign terrorist organisations," including al-Qaeda and the Palestinian group Hamas.