Washington - The Bush administration built an unprecedented surveillance operation to pull in mountains of information far beyond the warrantless wiretapping previously acknowledged, a team of federal inspectors general reported Friday, questioning the legal basis for the effort but shielding almost all details on grounds they're still too secret to reveal.

    The report, compiled by five inspectors general, refers to "unprecedented collection activities" by U.S. intelligence agencies under an executive order signed by President George W. Bush after the Sept. 11, 2001, terror attacks.

    Just what those activities involved remains classified, but the IGs pointedly say that any continued use of the secret programs must be "carefully monitored."

    The report says too few relevant officials knew of the size and depth of the program, let alone signed off on it. They particularly criticize John Yoo, a deputy assistant attorney general who wrote legal memos undergirding the policy. His boss, Attorney General John Ashcroft, was not aware until March 2004 of the exact nature of the intelligence operations beyond wiretapping that he had been approving for the previous two and a half years, the report says.

    Most of the intelligence leads generated under what was known as the "President's Surveillance Program" did not have any connection to terrorism, the report said. But FBI agents told the authors that the "mere possibility of the leads producing useful information made investigating the leads worthwhile."

    The inspectors general interviewed more than 200 people inside and outside the government, but five former Bush administration officials refused to be questioned. They were Ashcroft, Yoo, former CIA Director George Tenet, former White House Chief of Staff Andrew Card and David Addington, an aide to former Vice President Dick Cheney.

    According to the report, Addington could personally decide who in the administration was "read into" — allowed access to — the classified program.

    The only piece of the intelligence-gathering operation acknowledged by the Bush White House was the wiretapping-without-warrants effort. The administration admitted in 2005 that it had allowed the National Security Agency to intercept international communications that passed through U.S. cables without seeking court orders.

    Although the report documents Bush administration policies, its fallout could be a problem for the Obama administration if it inherited any or all of the still-classified operations.

    Bush brought the warrantless wiretapping program under the authority of a secret court in 2006, and Congress authorized most of the intercepts in a 2008 electronic surveillance law. The fate of the remaining and still classified aspects of the wider surveillance program is not clear from the report.

    The report's revelations came the same day that House Democrats said that CIA Director Leon Panetta had ordered one eight-year-old classified program shut down after learning lawmakers had never been apprised of its existence.

    The IG report said that President Bush signed off on both the warrantless wiretapping and other top-secret operations shortly after Sept. 11 in a single presidential authorization. All the programs were periodically reauthorized, but except for the acknowledged wiretapping, they "remain highly classified."

    The report says it's unclear how much valuable intelligence the program has yielded.

    The report, mandated by Congress last year, was delivered to lawmakers Friday.

    Rep. Jane Harman, D-Calif., told The Associated Press she was shocked to learn of the existence of other classified programs beyond the warrantless wiretapping.

    Former Bush Attorney General Alberto Gonzales made a terse reference to other classified programs in an August 2007 letter to Congress. But Harman said that when she had asked Gonzales two years earlier if the government was conducting any other undisclosed intelligence activities, he denied it.

    "He looked me in the eye and said 'no,'" she said Friday.

    Robert Bork Jr., Gonzales' spokesman, said, "It has clearly been determined that he did not intend to mislead anyone."

    In the wake of the new report, Senate Judiciary Committee Chairman Sen. Patrick Leahy, D-Vt, renewed his call Friday for a formal nonpartisan inquiry into the government's information-gathering programs.

    Former CIA Director Michael Hayden — the primary architect of the program_ told the report's authors that the surveillance was "extremely valuable" in preventing further al-Qaida attacks. Hayden said the operations amounted to an "early warning system" allowing top officials to make critical judgments and carefully allocate national security resources to counter threats.

    Information gathered by the secret program played a limited role in the FBI's overall counterterrorism efforts, according to the report. Very few CIA analysts even knew about the program and therefore were unable to fully exploit it in their counterrorism work, the report said.

    The report questioned the legal advice used by Bush to set up the program, pinpointing omissions and questionable legal memos written by Yoo, in the Justice Department's Office of Legal Counsel. The Justice Department withdrew the memos years ago.

    The report says Yoo's analysis approving the program ignored a law designed to restrict the government's authority to conduct electronic surveillance during wartime, and did so without fully notifying Congress. And it said flaws in Yoo's memos later presented "a serious impediment" to recertifying the program.

    Yoo insisted that the president's wiretapping program had only to comply with Fourth Amendment protections against search and seizure — but the report said Yoo ignored the Foreign Intelligence Surveillance Act, which had previously overseen federal national security surveillance.

    "The notion that basically one person at the Justice Department, John Yoo, and Hayden and the vice president's office were running a program around the laws that Congress passed, including a reinterpretation of the Fourth Amendment, is mind boggling," Harman said.

    House Democrats are pressing for legislation that would expand congressional access to secret intelligence briefings, but the White House has threatened to veto it.