WASHINGTON  A review of the Federal Bureau of Investigation’s scientific work on the investigation of the anthrax letters of 2001 concludes that the bureau overstated the strength of genetic analysis linking the mailed anthrax to a supply kept by Bruce E. Ivins, the Army microbiologist whom the investigators blamed for the attacks.

The review, by a panel convened by the National Academy of Sciences, says the genetic analysis “did not definitively demonstrate” that the mailed anthrax spores were grown from a sample taken from Dr. Ivins’s laboratory at Fort Detrick in Frederick, Md. It does add, however, that the evidence is “consistent with and supports an association” between Dr. Ivins’s flask and the attack anthrax.

The academy’s report faults the F.B.I. as failing to take advantage of scientific methods developed between the mailings in 2001 and its conclusion after Dr. Ivins’s suicide in 2008 that he was the sole perpetrator.

“In subsequent years, the investigators did not fully exploit molecular methods to identify and characterize” anthrax samples, the report said.