S. Rept. No. 107; H. Rept. No. 107: Joint Inquiry Into Intelligence Community Activities Before and After the Terrorist Attacks of September 11, 2001, Report of the U.S Senate Select Committee on Intelligence and U.S. House Permanent Select Committee on Intelligence, One Hundred Seventh Congress, Second Session, December, 2002 [open pdf - 5MB]
From the findings section within the document: "While in the United States, some of the September 11 hijackers were in contact with, and received support or assistance from, individuals who may be connected to the Saudi Government. There is information, primarily from FBI sources, that at least two of those individuals were alleged by some to be Saudi intelligence officers. The joint Inquiry's review confirmed that the Intelligence Community also has information, much of which has yet to be independently verified, indicating that individuals associated with the Saudi Government in the United States may have other ties to al-Qa'ida and other terrorist groups. The FBI and CIA have informed the Joint Inquiry that, since the September 11 attacks, they are treating the Saudi issue seriously, but both still have only a limited understanding of the Saudi Government's ties to terrorist elements. In their testimony, neither CIA not FBI witnesses were able to identify definitively the extent of Saudi support for terrorist activity globally or within the United States and the extent to which such support, if it exists, is knowing or inadvertent in nature. The FBI's Washington Fields Office created a squad devoted to […]. Only recently, and at least in part due to the Joint Inquiry's focus on the issue, did the FBI and CIA establish a working group to address the Saudi issue. In the view of the Joint Inquiry, this gap in U.S. intelligence coverage is unacceptable, given the magnitude and immediacy of the potential risk to U.S. national security. The Intelligence Community needs to address this area of concern as aggressively and as quickly as possible."
S. Rept. No. 107; Senate Report Number 107; H. Rept. No. 107; House Report Number 107.
U.S. Government Printing Office: http://www.gpo.gov/