However, General David Margolis, the associate deputy attorney, reviewed the ethics report as well as responses by Yoo and Bybee and decided not to adopt its findings and instead decided that they gave flawed legal advice.

During the Bush administration, Yoo and Bybee were high-ranking officials in the justice department's office of legal counsel.

The two lawyers "exercised poor judgment by overstating the certainty of their conclusions and underexposing countervailing arguments," Margolis said.

While he declined to refer concerns about the conduct by Yoo and Bybee to the state bar associations for possible disciplinary action, Margolis said they "can choose to take up the matter."

'Criminal charges'

Separately, a federal prosecutor is examining whether interrogators who relied on their advice should face criminal charges.

The outcome angered human rights groups who have pushed the Obama administration to pursue criminal charges, arguing that the harsh interrogations, which included a technique known as waterboarding, were forms of torture.

"The report underscores the need for a more thorough investigation that has more scope and powers to follow the evidence," said the Center for Constitutional Rights, a human rights group that has represented some former prisoners.

Waterboarding, which induces the sensation of drowning, was used on three terrorism suspects including Khalid Sheikh Mohammed, who has said he was the mastermind behind the September 11 attacks and Abu Zubaydah, an al-Qaeda suspect.

Yoo is currently employed as a law professor at the University of California at Berkeley and Bybee is a federal appeals court judge.