WASHINGTON — The Bush administration authorized secret surveillance activities that still have not been made public, according to a new government report that questions the legal basis for the unprecedented anti-terrorism program.

It's unclear how much valuable intelligence was yielded by the surveillance program started after the Sept. 11, 2001, terror attacks, according to the unclassified summary of reports by five inspectors general. The reports mandated by Congress last year were delivered to lawmakers Friday.

President George W. Bush authorized other secret intelligence activities — which have yet to become public — even as he was launching the massive warrentless wiretapping program, the summary said. It describes the entire program as the "President's Surveillance Program."

The report describes the program as unprecedented and raises questions about the legal grounding used for its creation. It also says the intelligence agencies' continued retention and use of the information collected under the program should be carefully monitored.

Many senior intelligence officials believe the program filled a gap in intelligence. Others, including FBI, CIA and National Counterterrorism Center analysts, said intelligence gathered by traditional means was often more specific and timely, according to the report.

The Bush White House acknowledged in 2005 that it allowed the National Security Agency to intercept international communications that passed through U.S. cables without court orders.

The inspectors general interviewed more than 200 government officials and private sector personnel, including former CIA and NSA Director Michael Hayden, former Defense Secretary Donald Rumsfeld and former Attorney General Alberto Gonzales.

Five former Bush administration officials refused to be interviewed, including former CIA Director George Tenet and former Attorney General John Ashcroft.

The others: former White House Chief of Staff Andrew Card; former top Cheney aide David Addington; and John Yoo, who served as a deputy assistant attorney general.

The IG report said an unnamed White House official inserted a paragraph into the first threat assessment prepared by the CIA after the Sept. 11 attacks, which was used to justify the extraordinary intelligence measures.

The paragraph said that the "individuals and organizations involved in global terrorism possessed the capability and intention to undertake further terrorist attacks within the United States," according to the report. It also said that the president should authorize the NSA to conduct the surveillance activities.