"FBIHQ should discuss this matter with other elements of the U.S. intelligence community and task the community for any information that supports Phoenix's suspicions," the agent recommended in the memo obtained by The Associated Press.
The FBI sent the intelligence to its terrorism experts in Washington and New York for analysis and had begun discussing conducting a nationwide canvass of flight schools when the Sept. 11 tragedies occurred, officials told AP.
At least one leader of the 19 hijackers, Hani Hanjour, received flight training in Arizona in 2001 but his name had not surfaced in the FBI intelligence from Arizona, the officials said.
Presidential spokesman Ari Fleischer declined to comment on the memo, saying he did not have "independent confirmation" from within the White House of its existence.
None of the Middle Eastern men identified by the Arizona counterterrorism agents or any information contained in their July 2001 memo pointed to the suicide plot that leveled the World Trade Center and killed thousands in New York, Washington and Pennsylvania, officials said.
"None of the people identified by Phoenix are connected to the Sept. 11 attacks," FBI Assistant Director John Collingwood said Thursday night.
"The Phoenix communication went to appropriate operational agents and analysts but it did not lead to uncovering the impending attacks," Collingwood said.
Officials said FBI counterterrorism agents in Phoenix were suspicious why several Arab men were seeking airport operations, security information and pilot training. The agents recommended that the FBI begin alerting local offices when Middle Easterners sought visas for training at local aeronautical schools.
"FBIHQ should consider seeking the necessary authority to obtain visa information from the USDOS (State Department) on individuals obtaining visas to attend these types of schools and notify the appropriate FBI field office when these individuals are scheduled to arrive in their area of responsibility," the memo said.
The FBI's concerns about the U.S. flight schools is the latest revelation about information, much of it sketchy, that the government possessed before Sept. 11 concerning the possibility of terrorism in the skies. For example:
AP reported last month that Filipino authorities alerted the FBI as early as 1995 that several Middle Eastern pilots were training at American flight schools and at least one had proposed hijacking a commercial jet and crashing it into federal buildings.
A month after the 2001 memo from Arizona to FBI headquarters, FBI agents in Minnesota arrested a French citizen of Moroccan descent, Zacarias Moussaoui, after a flight school instructor became suspicious of his desire to learn to fly a commercial jet.
Moussaoui has since emerged as the single most important defendant in the post-Sept. 11 terrorism investigation, charged with conspiring with the hijackers and Osama bin Laden to kill thousands of Americans. Prosecutors are seeking the death penalty.
About the same time as the Phoenix memo and Moussaoui's arrest, U.S. intelligence issued a late summer warning that there was heightened risk of a terrorist attack on Americans, possibly even on U.S. soil, officials have said.
Law enforcement officials said in retrospect the FBI believes it should have accelerated the suggested check of U.S. flight schools after Moussaoui's arrest but does not believe it would have led to the hijackers.
FBI officials said a supervisory agent in Arizona wrote a several-page memo to FBI headquarters in July 2001 laying out information his counterterrorism team had developed in an unrelated investigation. A portion of the memo dealt with an Arizona flight school, officials said.
The memo indicated agents were suspicious about why several nonresident Arab men were seeking training at a commercial aeronautical school in Prescott, Ariz.
Collingwood said the men "were enrolled in various aspects of civil aviation engineering, airport operations and pilot training." The agents were particularly concerned that some were attempting to learn about airport security operations, officials said.
The Phoenix memo urged FBI headquarters to assemble a list of U.S. aviation academies and to instruct field offices across the country to make "appropriate liaison" with their local schools where other Middle Easterners might be training.
The information was shared with intelligence analysts who monitored terrorist threats and was even sent to the FBI office in New York that had the most experience with terrorism cases, officials said.
After the suicide attacks, the FBI quickly descended upon flight schools nationwide, identifying academies in Florida, Arizona and elsewhere where the leaders of the 19 hijackers trained.
Hanjour, believed to have piloted the jetliner that crashed into the Pentagon, trained at a flight academy in Phoenix between January and March 2001, the government has said in court documents.
Some witnesses have also said they believe another hijacker, Ziad Samir Jarrah, trained on an Arizona flight simulator in the months before the attacks. But the FBI has no evidence that either man was connected to the Prescott school identified in the July 2001 memo, officials said.
The FBI also investigated whether an Algerian pilot who spent time in Arizona may have helped train the hijackers before leaving the United States before the attacks.
That man, Lotfi Raissi, was later apprehended in Britain, but U.S. officials failed to persuade a court there to extradite him to the United States. Law enforcement officials say their suspicions about his connections to the hijackers have since fizzled.
An Arizona businessman who assisted U.S. intelligence said he alerted the FBI in the mid-1990s that one or more Middle Eastern pilots were training or working in his state and appeared suspicious.
Harry Ellen said he told an FBI agent in Phoenix in late 1996 or early 1997 that he met an Algerian pilot and several Middle Eastern men at an Arizona mosque. Ellen assisted U.S. intelligence during the 1990s but later had a falling out over his business and personal dealings in Asia and the Middle East.
"I brought this to the attention of an agent in the local FBI whom I knew," Ellen said. "They did not seem particularly interested in the presence of these people. I stressed it was very odd that the Algerian man was involved in aviation."
"One of the other men I believe was probably Mr. Raissi, although he would have been thinner and younger at the time," Ellen said.
Law enforcement officials said that while Ellen helped the FBI, agents in Arizona have no record or recollection of him providing information about pilots.