A report in the Washington Post said that over seven months, the FBI director Christopher Wray had mentioned the bogus higher figure as the main reason why law enforcement needed a way to get pas encryption.
The FBI claimed that it became aware of the bloated figures a month back and still did not have an accurate count of how many encrypted phones were received as part of investigations in 2017.
It blamed "programming errors" for the wrong numbers. But it said that despite the stuff-up "going dark remains a serious problem for the FBI, as well as other federal, state, local and international law enforcement partners. ... The FBI will continue pursuing a solution that ensures law enforcement can access evidence of criminal activity with appropriate legal authority".
Their reaction came in a letter to Wray about the agency's actions in the 2016 stoush with Apple, over gaining access to an iPhone 5C belonging to a terrorist who had killed Americans in San Bernardino, California, in December 2015.
In March 2016, the agency obtained a court order, asking the company to supply a new version of its mobile operating system, iOS, which did not have certain locking functions, so that it could attempt to guess the passcode on the iPhone 5C by using a brute force method.
When Apple resisted, the FBI came back with an order compelling the company to fall in line.
After some to-ing and fro-ing, in March 2017, the FBI ended the stoush, saying it had gained access to the iPhone in question.
The Post said that Wray had first cited the inflated statistics in October last year, claiming nearly 7000 encrypted devices were part of investigations over the previous 11 months.
Two months later, he told the US Congress that in the 2017 budget year, the FBI “was unable to access the content of approximately 7800 mobile devices using appropriate and available technical tools, even though there was legal authority to do so".
The incorrect claim about encrypted device could "fuel further criticism from lawmakers, privacy advocates and tech companies, and hinder the bureau’s public efforts to address encryption issues", the Post said.