Washington ? “Extraordinary and inappropriate” secrecy about a warrantless eavesdropping program undermined its effectiveness as a terrorism-fighting tool, government watchdogs have concluded in the first examination of one of the most contentious episodes of the Bush administration.

A report by inspectors general from five intelligence agencies said the administration’s tight control over who learned of the program also contributed to flawed legal arguments that nearly prompted mass resignations in the Justice Department five years ago.

The program “may have” contributed to successful counterterrorism efforts, some intelligence officials told the investigators. But too few CIA personnel knew of the highly classified program to use it for intelligence work, the report stated, while at the FBI, the program “played a limited role,” with “most (leads) determined not to have any connection to terrorism.”

The surveillance program, which intercepted domestic communications linked to people with suspected ties to al-Qaida, was one of the Bush administration’s most secretive and, eventually, controversial intelligence efforts. After the New York Times disclosed its existence in December 2005, the program became a symbol of the administration’s expansive view of executive authority, especially regarding national security.

“The surveillance program was overly secret and its importance overblown,” concluded Gregory Nojeim, senior counsel of the privacy advocacy organization Center for Democracy and Technology, after reading the report.

Friday’s release of the inspectors general’s summary findings renewed questions about the effectiveness of congressional oversight of intelligence activities, after a week of back-and-forth between House members and the CIA over an unrelated classified program that has been squashed by the new administration. The IGs reported that lawmakers received 49 briefings on the surveillance program between October 2001 and January 2007.

House Speaker Nancy Pelosi, D-Calif., said: “The legal analysis under which the program operated for years ‘entailed ignoring an act of Congress, and doing so without full congressional notification.’ No president should be able to operate outside the law.”

The report also inspired fresh calls from congressional Democrats, including the chairmen of the House and Senate Judiciary committees, to establish a commission to explore the Bush administration’s handling of its anti-terrorism efforts. The lawmakers pointed out that several key Bush administration figures refused to cooperate with the inspectors general, who lacked the authority to compel testimony.

Significant elements of the initiative are still unclear. But an unclassified version of the inspectors general’s report offers new details about its origins.

The clandestine program was born in the days after Sept. 11, 2001, when then-CIA Director George Tenet asked the National Security Agency’s chief, Lt. Gen. Michael Hayden, “what he might do with more authority,” the report said. A short while later, President George W. Bush signed a single document paving the way for the plan.