In the letter, Grassley asked for an investigation into how the FBI handled a now-infamous July 2001 memo from the FBI's Phoenix, Ariz., field office recommending that the bureau keep an eye on flight schools, obtain visa information on enrolled pilots and coordinate a nationwide investigation. That memo reportedly stressed concern about a connection between Middle Eastern flight students in Arizona with Osama bin Laden.
FBI Director Robert Mueller told a Senate panel last week that memo likely did not make it to high levels of the FBI or the CIA and that the agency should have made it a higher priority.
"This memo has emerged as one of the most significant and alarming warnings that the FBI had before the terrorist attacks of Sept. 11, 2001," Grassley wrote. "It is essential that there be an outside review of this matter by your office to answer all outstanding questions, ensure accountability at the FBI and reaffirm the trust of the American people."
In a separate letter Wednesday, Grassley also called on FBI Director Robert Mueller to make the memo available to the public. "I strongly urge you not to invoke secrecy in the way the government so often does: as an excuse to prevent the release of embarrassing information," Grassley wrote.
The letters reflect increasing concern among Democrats and Republicans in Congress that the Bush administration is stonewalling congressional inquiries into whether U.S. intelligence agencies missed, bungled or ignored what appear to be important warning signs of a pending airline terror attack -- in the weeks prior to Sept. 11.
Senate Judiciary Committee Chairman Sen. Patrick Leahy, D-Vt., this week also sent 19 pages of questions to Bush administration officials, mostly for FBI Director Robert Mueller, about U.S. intelligence actions prior to the Sept. 11 attacks.
The questions posed by Leahy, a Vermont Democrat, seek facts about:
-- How the FBI handled the July 2001 Phoenix memo.
-- Information on the August 2001 arrest of Zacarias Moussaoui, the alleged "20th hijacker," for visa violations after he raised the suspicions of an instructor at a flight school in Eagan, Minn. Leahy is particularly interested in FBI efforts to obtain information from Moussaoui, his computer, and his apartment.
-- Facts about a warning from French intelligence officials at least 10 days before Sept. 11 that Moussaoui had connections to radical Islamic extremists.
-- Press reports that in 1995 Filipino authorities warned the FBI that a Middle Eastern pilot trained at a U.S. flight school had proposed crashing a jet into federal buildings.
-- How the FBI has handled information that potential terrorists have taken advantage of U.S. flight schools. The FBI confirmed for United Press International this week that some individuals mentioned in the July 2001 Phoenix memo were not involved in the Sept. 11 attacks and are still under investigation.
Senate Intelligence Committee Chairman Bob Graham, D-Fla., is also seeking a personal meeting with Attorney General John Ashcroft, for this week if possible, to demand "cooperation with enthusiasm" instead of "cooperation out of grudging necessity" on that committee's investigation. Republicans on the committee agree with Graham.
Early this year, President Bush and Vice President Dick Cheney both personally asked Senate Majority Leader Tom Daschle, D-S.D., to limit any investigation to only the House and Senate Intelligence Committees -- the same investigation that Graham and some Republicans are complaining the administration is now stonewalling.
At the time, Daschle said "the vice president expressed concern that a review of what happened would take resources and personnel away from the effort in the war on terrorism." But Daschle added that the "the American people have a right to know what happened and why."
Leahy and Orrin Hatch, R-Utah, Judiciary Committee ranking member, in February asked for $1.5 million for their committee to conduct their own investigation. But Majority Leader Trent Lott, R-Miss, blocked the request, according to Leahy.
"Senator Hatch and I have made a joint request for additional funding to examine the events leading up to the Sept. 11 attacks and what steps are needed to make sure that our law enforcement is in a position not to let history repeat itself," Leahy said last week.
"That request has been blocked by Minority Leader Lott. An examination of FBI operations before 9/11 are essential, not to lay blame, but to learn lessons and to be in a position to evaluate the FBI reorganization plans."
Ron Bonjean, spokesman for Lott, said that the investigation should be left to the Intelligence Committee so that the Judiciary Committee can concentrate on confirming the president's judicial nominations.
"I realize that the House and Senate Select Intelligence Committees are conducting a joint review of factors and events that led up to the attacks and I appreciate their work," Grassley wrote to the DOJ Inspector General. "However, their investigation comes from a different perspective, and it certainly does not preclude the Judiciary Committee from carrying out its oversight responsibilities."
(UPI Congressional Bureau Chief Mark Benjamin and UPI Senior White House Correspondent Nicholas M. Horrock contributed to this report.)