The FBI agent who wrote a pre-Sept. 11 warning about Arab students at an Arizona flight school hoped his memo would lead to screenings of Middle Easterners who came to study U.S. airport operations, according to government officials familiar with his account.

Agent Kenneth Williams testified behind closed doors Tuesday to lawmakers investigating what the government knew about terrorist threats before Sept. 11.

Williams believed his information might provide a significant but prospective lead about Usama bin Laden's intentions, according to lawmakers and government officials familiar with his account.

But Williams wrote his memo for terrorism experts in Washington and never intended the memo — which was written in the standard electronic communication format — to reach the highest levels of government, according to several people familiar with his account, who spoke only on condition of anonymity.

Williams told investigators that while the information he learned about students already in aviation training prompted his memo, he also was concerned about prospective students coming to the United States to learn about airline security, operations and flying to help bin Laden carry out an attack, the officials said.

Williams did not believe the information he had about the eight Arab students in Arizona identified in the memo was significant and specific enough to warrant action like arrests, the sources said.

That's why he proposed that flight schools across the country be canvassed to identify other possible students, and urged that immigration officials notify local FBI offices when new students came into the country, according to the officials.

"I believe he thought he was investigating a matter of significance," Sen. Arlen Specter, R-Pa., said after the briefing.

In response to one question during his closed-door session Tuesday, Williams said he did not believe any of the information he knew last summer directly involved the Sept. 11 hijacking plot, officials said.

FBI Director Robert Mueller also attended the closed-door briefing, telling lawmakers he first learned of Williams' July 10, 2001, memo a few days after the Sept. 11 attacks.

By that time, Mueller told the lawmakers, Williams' idea for canvassing flight school was already under way because of information learned about where the 19 hijackers had trained.

The rare appearance by a field agent at a closed door session with lawmakers came as the FBI sought to make the case that much of Williams' memo was speculative, and did not point directly to the Sept. 11 attacks.

Lawmakers pressed Mueller about where Williams' information had circulated before and immediately after Sept. 11 and one senator expressed frustration afterward.

"One thing that's clear is that prior to Sept. 11, the FBI information process regarding counterterrorism was a mess," said Sen. Charles Grassley, R-Iowa. "And, even to this day, no one seems to know who knew what and where critical information went at FBI headquarters."

"It does appear that FBI leadership is now trying to centralize the process, but I'm not convinced they've done it yet because they still don't have answers to what or why things fell apart before Sept. 11."

Williams told congressional investigators that information counterterrorism and national security investigations identified about eight Arab students who were attending various types of training at an aeronautical training school in Prescott, Ariz.

The agent said intelligence and surveillance under national security warrants suggested one of the students might be a bin Laden sympathizer because he had a picture of the accused terrorist, the officials said.

Phone records or intercepts identified a second student who had talked to an associate who had made contact once with a known Al Qaeda operative, officials said.

Williams and other terrorism experts inside the FBI ran the names of suspect flight students through intelligence and found no known links to Al Qaeda, the government sources said.

But based on the two circumstantial pieces of information and a growing intelligence that bin Laden was agitating to strike, Williams sent the memo to FBI headquarters with introductory language suggesting bin Laden might be organizing training for some students at U.S. flight schools, the officials said.