* Order bars material support, freezes financial assets
* Prosecutors charge TTP leader for attack on U.S. base
* $5 million reward offered for top leaders (Adds quotes, details)
By Andrew Quinn
WASHINGTON, Sept 1 (Reuters) - The United States on Wednesday added the Pakistani Taliban to its list of foreign terrorist organizations and set rewards of up to $5 million for information leading to the capture of two of its leaders.
The steps mark Washington's toughest moves against the Tehrik-i-Taliban, or Taliban Movement of Pakistan (TTP), a group that claimed responsibility for the failed bomb plot in New York's Times Square and is increasingly seen as a direct threat to the United States.
"We should be very clear about this. The TTP is very much a part of the most dangerous terrorist threat that the United States faces," Daniel Benjamin, the State Department's ambassador at large for counterterrorism, told a news briefing.
Secretary of State Hillary Clinton's move, announced in a note in the Federal Register, adds the TTP to a list of some 46 groups the United States deems involved in terrorism and subjects to financial and travel sanctions.
Simultaneously, U.S. prosecutors charged TTP leader Hakimullah Mehsud for a plot that killed seven CIA employees at a U.S. base in Afghanistan last December, and U.S. officials offered $5 million rewards for information leading to the arrest of Mehsud and Wali-ur-Rehman, another senior TTP commander.
"These individuals are dedicated terrorists and they are attempting to extend their bloody reach into the American homeland," said Robert Hartung, a senior State Department security official.
U.S. military forces have tried to kill Mehsud using unmanned aerial drones since the December attack. Both men are believed to be in the tribal areas of northwestern Pakistan, a haven for militant groups such as the TTP.
Benjamin called the TTP a "force multiplier" for al Qaeda, expanding its reach around the world. The organization also has ties to Punjabi militant groups and is suspected of being behind most bomb and suicide attacks across Pakistan.
The TTP claimed responsibility for being behind the botched bomb plot in New York's Times Square in May, an attack analysts said showed the militant group sought to bring its violent campaign to U.S. shores.
More recently, the TTP claimed responsibility for attacks in Lahore in May that killed between 80 and 95 members of the minority Ahmadi sect.
Washington sees Pakistan as a frontline state in its war against the Taliban and al Qaeda and has named a number of Pakistani militant groups to its blacklist, aimed at curtailing support for terrorist activities and squeezing them financially.
ALLIANCE OF MILITANT GROUPS
The TTP was formed in December 2007 as an alliance of Pakistani militant groups to attack the Pakistani state. It believes the government is illegitimate because it is helping NATO and the United States in neighboring Afghanistan.
The group managed to wrest large swathes of territory in the border area from government control before being driven back. But it is widely considered to remain a potent threat.
In the December attack at the U.S. base in Afghanistan, a Jordanian doctor who won the trust of CIA employees detonated a bomb hidden under his clothing after entering the heavily-armed compound outside Khost.
The U.S. Justice Department on Wednesday charged Mehsud with conspiracy to kill Americans overseas and conspiracy to use a weapon of mass destruction -- in this case, a suicide bomber.
"Criminal charges are meant to deal with Hakmullah if he's captured," said one U.S. official, who declined to be further identified. "He can face justice in other ways too. That hasn't changed."
The TPP hit the U.S. headlines again after the Times Square bomb attempt, which saw a naturalized U.S. citizen of Pakistani origin arrested after he parked a sport utility vehicle rigged with a crude explosive device that included firecrackers and propane gas tanks in New York's main tourist hub.
Faisal Shahzad later pleaded guilty and said he had received bomb-making training and $12,000 from the TTP in Pakistan to facilitate the bomb attempt. U.S. officials say there is credible information to support the TTP's claim of responsibility. (Additional reporting by Jeremy Pelofsky in Washington Quinn; Editing by Vicki Allen and Jerry Norton)