U.S. prosecutors have charged the leader of the Pakistani Taliban, Hakimullah Mehsud, in the plot that killed seven CIA employees at an American base in Afghanistan last December, the Justice Department said on Wednesday.

Mehsud, believed to be hiding in the tribal areas of Pakistan and head of the group known as Tehrik-e-Taliban Pakistan, was charged with conspiracy to kill Americans overseas and conspiracy to use a weapon of mass destruction.

On December 30, a Jordanian doctor who had gained the trust of the CIA employees as a source detonated a bomb hidden under his clothing after entering a heavily fortified compound outside Khost. It was the second-most deadly attack in CIA history.

"Criminal charges are meant to deal with Hakimullah if he's captured," said a U.S. official who declined to be identified. "He can face justice in other ways, too. That hasn't changed."

U.S. military forces have tried to kill Mehsud since the attack with strikes by unmanned aerial drones. The State Department is offering a reward of up to $5 million for information leading to his location.

There were reports in January that Mehsud was killed in a drone strike but he later appeared in Internet videos threatening suicide strikes in the United States. The tribal areas of Pakistan have become a haven for the Taliban and al Qaeda militants.

Tehrik-e-Taliban Pakistan also claimed responsibility for the failed attempt to detonate a car bomb in New York's Times Square on May 1.

After the attack on the CIA employees, a video surfaced in which the bomber, identified as Jordanian Humam Khalil Abu Mulal al-Balawi, appeared with Mehsud claiming responsibility for the suicide bombing and stating that it was revenge for the killing of the group's leader, Baitullah Mehsud.

"We arranged together this attack to let the Americans understand that the belief of Allah, the iman (faith) that we hold, the taqwa (piety) that we strive for cannot be exchanged for all the wealth in the world," they said in the video according to an FBI affidavit filed with the complaint.

Al-Balawi's legs were recovered from the scene of the blast and DNA testing helped identify him, according to the complaint which was filed in U.S. District Court for the District of Columbia.

Six Americans were also injured in the attack.

(Reporting by Jeremy Pelofsky, editing by Vicki Allen and Chris Wilson)