The FBI told the US Congress for months that its investigators were locked out of nearly 7,800 devices in 2017, despite having a court order to the data contained on the phones.
The Washington Post, however, has reported the statistic is inflated and is probably between 1,000 and 2,000 devices.
According to the report, the FBI learned of the miscount in April and still does not have an accurate figure for the number of encrypted phones it received.
An internal estimate from last week put the correct number of locked phones at 1,200. The report stated that officials expect the number to change as they launch a new audit, which could take weeks to complete.
The FBI said that counting errors aside, the phenomenon of “Going Dark” remains a problem for the bureau and law enforcement around the world.
It said it will continue pursuing a solution that ensures law enforcement can access evidence of criminal activity with appropriate legal authority.