Washington ? The inability to detect the Sept. 11, 2001, hijacking plot amounts to a “significant failure” by the FBI and was caused in large part by “widespread and long-standing deficiencies” in the way it handled terrorism and intelligence cases, according to a new report released Thursday.

In one particularly notable finding, the report by Justice Department Inspector General Glenn Fine concluded the FBI missed at least five chances to detect the presence of two of the suicide hijackers – Nawaf al Hazmi and Khalid al Mihdhar – after they first entered the United States in early 2000.

“While we do not know what would have happened had the FBI learned sooner or pursued its investigation more aggressively, the FBI lost several important opportunities to find Hazmi and Mihdhar before the September 11 attacks,” the report said.

Although many of the missteps surrounding Hazmi and Mihdhar have become well known, Fine’s report adds details about the FBI’s role in fumbling the case. Previous reports, including the best-selling tome by the independent Sept. 11 commission, focused more heavily on the CIA’s failure to track the men after a pivotal terrorist summit meeting in Malaysia.

The FBI said in a statement that it agreed with many of Fine’s conclusions but “has taken substantial steps to address the issues presented in the report.”

“Today, preventing terrorist attacks is the top priority in every FBI office and division, and no terrorism lead goes unaddressed,” the FBI said.

The 371-page report is the latest in a stream of assessments from Congress, the 9-11 panel and other investigators documenting serious shortcomings in the performance of various U.S. government agencies in the months before the hijackings. It also comes amid a wave of criticism of the FBI in recent months over a scrapped $170 million software program and its continuing struggle to attract qualified analysts, translators and other intelligence personnel.

Fine’s investigation was requested by FBI Director Robert Mueller shortly after the 9-11 attacks.