WASHINGTON -- Thirteen days before the Sept. 11 attacks, a frustrated FBI agent warned headquarters that "someday, someone will die" after he was denied permission to pursue a man who would become one of the hijackers, a congressional panel was told Friday.

The agent's efforts were among many missed opportunities to stop two of the hijackers after they were spotted attending an al-Qaida meeting in Malaysia in January 2000, according to the report to the House and Senate Intelligence Committees.

It was the latest revelation of missed clues by intelligence and law enforcement authorities before the attacks.

Poor communications between the CIA and FBI -- partly caused by legal restrictions -- and limited counterterrorism staff kept authorities from aggressively pursuing the two hijackers, lawmakers were told.

The committees have been meeting since June, conducting an inquiry into intelligence agencies' counterterrorism efforts before the attacks. On Friday, President Bush reversed course and backed efforts by many lawmakers to have an independent commission conduct a broader investigation.

But Stephen Push, a leader of a group of Sept. 11 relatives, said Bush's proposal isn't good enough because it apparently wouldn't include an investigation of the intelligence agencies themselves.

"This is disgraceful, what we're learning about intelligence failures, and the White House is trying to cover it up," he said.

In her report Friday, inquiry staff director Eleanor Hill said two hijackers, Khalid al-Mihdhar and Nawaf al-Hazmi, were able to live openly in San Diego even after they were spotted in the Malaysia meeting. They used their true names on an apartment lease and al-Mihdhar obtained a driver's license. They also took flight lessons. They could obtain and renew visas, and leave and re-enter the United States.

Not until Aug. 23, 2001, were they put on the State Department's watch list for denying visas. Even after that, the New York-based FBI agent was denied permission by headquarters to use his office's full resources to find al-Mihdhar.

In an e-mail, headquarters denied the request because al-Mihdhar was not under criminal investigation. It cited the "wall" between intelligence and law enforcement.

The unidentified agent replied: "Someday someone will die -- and wall or not -- the public will not understand why we were not more effective and throwing every resource we had at certain problems."

The agent appeared at Friday's hearing, sitting alongside an unidentified CIA officer. Their backs and sides were shielded by a screen, revealing their faces only to lawmakers and their staff.

He recalled learning the hijackers' identities after Sept. 11.

"When I heard the name Khalid al-Mihdhar, I was upset," he said. "I remember explaining this is the same Khalid al-Mihdhar we had talked about for three months."

Through hearings this week and some in the future, Hill is painting a picture of missed opportunities. Individually, none may have prevented the attacks. But collectively, they might have unraveled the plot.

The missed opportunities also include the FBI's failure to follow up a memo by a Phoenix agent warning that U.S. flight schools may be training terrorist pilots and its refusal in August 2001 to pursue a warrant to search the computer of Zacarias Moussaoui, now charged with conspiring in the attacks.

Against that is the backdrop of a report Hill presented Wednesday: that U.S. intelligence agencies were receiving many vague reports of possible terrorist attacks. At least 12 suggested the use of airplanes as weapons.

In neither the CIA nor FBI "did anyone see the potential collective significance of the information, despite the increasing concerns throughout the summer of 2001 of an impending terrorist attack," Hill said.

In May, Bush's national security adviser, Condoleezza Rice, had said no one could have predicted terrorists would try to use an airplane as a missile. On Friday, she acknowledged "somebody did imagine it." But she said she did not know about the intelligence until well after May.

Asked if she should have known about it, she said, "There are always shards of intelligence and of different kinds of analysis. I mean, how do you stack it up against hundreds of reports about car bombs? So I wouldn't make that claim."

In her report Friday, Hill said she has found no indication that authorities had information about 16 of the 19 hijackers. It had limited information about al-Hazmi's brother, Salim-al-Hazmi, who, like the other two, was on the plane that crashed into the Pentagon.

Hill said CIA interest in the Malaysia meeting faded after January 2000, gradually resurfacing after a participant was linked to the October 2000 attack on the USS Cole in Yemen.

But the CIA gave limited information about the Malaysia meeting to FBI agents investigating the Cole attack, Hill said. Part of the reason was the legal restriction on the use of foreign intelligence in criminal prosecutions. Congress modified those restrictions shortly after the Sept. 11 attacks.

CIA officials have acknowledged they could have handled intelligence on the Malaysia meeting better, but maintain they provided the FBI information on al-Mihdhar and al-Hazmi well before the attacks.

The FBI agent who sent the Aug. 23 e-mail urged intelligence committee members to ease those restrictions.

Sen. Carl Levin, D-Mich., praised the agent's work and lamented his anonymity.

"You will never receive the public recognition that you deserve for what you tried to do, for your e-mails, for your efforts to break down walls, reals and imaginary, for your effort to break through bureaucracy," he said.