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WASHINGTON, July 12 (Reuters) - The CIA withheld information from Congress about a secret counterterrorism program on orders from former U.S. Vice President Dick Cheney, a leading U.S. senator said on Sunday.

Democratic Senator Dianne Feinstein told Fox News Sunday that CIA Director Leon Panetta disclosed Cheney's involvement when he briefed members of Congress two weeks ago. She said Panetta told them he had canceled the program.

President Barack Obama appointed Panetta to head the agency early this year. The still-secret program, which The New York Times said never became operational, began after the Sept. 11 attacks on the United States.

News of Cheney's involvement, first reported by the Times late on Saturday, prompted an outpouring of criticism by Obama's fellow Democrats and support by rival Republicans in Congress.

Feinstein, chairman of the Senate Intelligence Committee, said: "Director Panetta did brief us two weeks ago -- I believe it was on the 24th of June -- ... and, as had been reported, did tell us that he was told that the vice president had ordered that the program not be briefed to the Congress."

Feinstein and Democrat Patrick Leahy, chairman of the Senate Judiciary Committee, insisted no one should go outside the law.

Asked about Cheney's involvement, Leahy told CBS's Face the Nation: "I'd like to know if it's true or not. I mean, nobody in this country is above the law ... You can't have somebody say, well, if you're vice president, you don't have to obey the law."

Feinstein said Congress "should have been told" about the secret problem and that the vice president shouldn't be above the law.

"This is a big problem, because the law is very clear. And I understand the need of the day, which was when America was in shock" after Sept. 11, she said on Fox. "But ... I think you weaken your case when you go outside of the law."

Cheney was a key advocate in the Bush administration of using controversial interrogation methods such as waterboarding on terrorism suspects and has emerged as a leading Republican critic of Obama's national security policies.

Since Obama took over from President George W. Bush on Jan. 20, Cheney has engaged in an increasingly contentious battle with the new administration over the CIA interrogation procedures that undermined the United States's reputation around the world.

In one of his first acts as president, Obama ordered more humane treatment for terrorism suspects.

Panetta has vowed not to allow coercive interrogation practices, secret prisons or the transfer of terrorist suspects to countries that may use torture, a pledge seen as a break with the agency's policies under Bush.

Republican Senator Jeff Sessions, the ranking Republican on the Judiciary Committee, told "Face the Nation" he said he believed the Cheney allegations will be investigated.

Asked if he expected the situation to be looked into, Sessions said: "Well, I'm sure it will be."

"I don't know what the facts are. But I believe that Vice President Cheney served his country with as much fidelity as he could possibly give to it. And he tried to serve us in an effective way. And I hope that nothing like this would impact on his outstanding record."