The head of the CIA never informed a vacationing President George W Bush in August 2001 that a suspected Islamic extremist had been detected taking flight lessons, says the panel investigating the September 11th airliner attacks.
CIA director Mr George Tenet also told the commission probing the incidents, in which nearly 3,000 people were killed, that he did not tell other senior officials of the matter, saying it was "not appropriate."
Commissioner Mr Tim Roemer, a former Democratic congressman, asked Mr Tenet if he had ever mentioned to President Bush the arrest of Zacarias Moussaoui in mid-August 2001 after he had been detected behaving suspiciously in a Minnesota flight school.
Mr Tenet said he had not spoken to the president at all that month, when President Bush was staying at his ranch in Crawford, Texas.
"He's in Texas and I'm either here or on leave for some of that time," he said. "In this time period, I'm not talking to him, no."
After Moussaoui's arrest, Mr Tenet and other top CIA officials received a briefing headed, "Islamic Extremist Learns to Fly."
But the CIA director did not bring it up at a meeting of top administration officials to discuss Osama bin Laden's al Qaeda organisation on September 4th, a week before the attacks.
"It wasn't discussed at the principals' meeting since we were having a separate agenda," Mr Tenet said. "All I can tell you is just it wasn't the appropriate place. I just can't take you any farther than that."
Moussaoui, who was originally detained for immigration violations, was later charged with conspiracy in connection with the September 1th1 attacks, and faces a possible death penalty if convicted.
Mr Tenet came under tough questioning, with Republican commissioner Mr John Lehman calling the staff report a "damning evaluation of a system that is broken."
But Mr Tenet said the report was wrong to state he had no strategic plan to manage the war on terrorism or to integrate and share data across the intelligence community.
However, Tenet did acknowledge that his and other agencies failed to devise an effective defence against bin Laden's al Qaeda operatives in 2001.
"We all understood bin Laden's attempt to strike the homeland. We never translated this knowledge into an effective defence of the country," Mr Tenet said.
"No matter how hard we worked, or how desperately we tried, it was not enough. The victims and the families of 9/11 deserved better."