WASHINGTON (MCT) — Despite the Bush administration's insistence that its warrantless eavesdropping program was necessary to protect the country from another terrorist attack, FBI agents, CIA analysts and other officials had difficulty evaluating its effectiveness, according to an unclassified government report made public Friday.

The CIA made no effort to document how the program had contributed to counterterrorism successes, and CIA officials saw it as just "one source among many available analytic and intelligence-gathering tools," the report said.

"Consequently, it is difficult to attribute the success of (any) particular counterterrorism case exclusively to the (program)," it said.

The report, written by inspectors general from the CIA, Pentagon, Justice Department, National Security Agency and the Office of Director of National Intelligence, also faulted the Bush White House for its secretive handling of the program.

Bush officials so restricted access to information about the program that Justice Department officials couldn't properly monitor it — or even judge its legality, the inspectors general concluded.

The program was secret until 2005, when The New York Times revealed its existence. The news provoked an outcry from civil liberties groups and members of Congress, including some Republicans.

The Bush administration asserted the president had the power to authorize eavesdropping without court oversight because at least one party was suspected of supporting or engaging in terrorist activities. In 2007, however, the Bush administration abandoned that position and said it would seek warrants for its surveillance program from a special national security court.

The 38-page report is an unclassified version of a much longer document, hundreds of pages of which remain secret.

The short version offered new details of the sometimes dramatic clashes between administration officials over the program's legality, but it left unanswered questions about the extent of the eavesdropping and whether any abuses occurred.

Investigators interviewed about 200 officials, but several former high-level officials — including former White House Chief of Staff Andrew Card, former Attorney General John Ashcroft, former Justice Department lawyer John Yoo and former counsel to the vice president David Addington — refused to be interviewed, hobbling the probe.

(EDITORS: BEGIN OPTIONAL TRIM)