July 10 (Bloomberg) -- A wiretapping program conducted by the Bush administration without court search warrants after the 2001 terrorist attacks lacked adequate legal supervision, a report by five U.S. inspectors general said.

The legal justification for the program was written by Justice Department lawyer John Yoo, and his legal rationale was later found to be flawed, the report said. It was “extraordinary and inappropriate” that Yoo single-handedly was in charge of conducting the legal review of the program, the report said. A declassified summary of the report was released today.

Under the program, the National Security Agency tapped international phone calls, that passed through U.S. telecommunications facilities, of people suspected of being members of terrorist groups or associating with them.

Congress asked for the report on the program last year and the 38-page document that was released today is a summary of a larger classified document provided to lawmakers. The report was prepared by the inspectors general of the Central Intelligence Agency, the Justice and Defense Departments, the National Security Agency and the Office of the National Intelligence Director.

“President Bush’s warrantless surveillance program was illegal from the beginning and of questionable value,” said House Judiciary Committee Chairman John Conyers, a Michigan Democrat, in an e-mailed statement.

The report found that Yoo’s immediate supervisor, Jay Bybee, wasn’t aware that Yoo was even working on the project, according to the report. The program was kept in the strictest secrecy under the direction of President George W. Bush, the report found.

Efforts to reach Bybee and Yoo were unsuccessful.

The report said some intelligence professionals believed the program “filled a gap” in the nation’s intelligence efforts. Others, including analysts at the Federal Bureau of Investigation and CIA, “had difficulty evaluating the precise contribution” of the program.

To contact the reporter on this story: Christopher Stern in Washington at cstern3@bloomberg.net

Last Updated: July 10, 2009 19:49 EDT