The US Transportation Security Administration (TSA) has revealed industry secrets about airport passenger screening practices by accidentally publishing an in-house manual online.
The TSA operating manual was posted on a federal procurement website earlier this year as part of a contract request, according to the Washington Post.
The manual gives details of technical settings of X-ray machines and explosives detectors and other passenger and luggage screening details.
The document includes images of credentials used by members of Congress, CIA employees and federal air marshals, and identifies 12 countries automatically subjected to added scrutiny.
Current and former security officials said the breach was troubling because increased the risk of people bypassing measures introduced after the World Trade Center attack in 2001.
A former Department of Homeland Security official said the breach was serious, but another former DHS official said TSA manuals are shared widely with airlines and airports.
"While it's certainly a type of document you would not want to be released . . . it's not something a determined expert couldn't find another way," the official said.
The manual was posted on the Internet in redacted form, but blacked-out passages were easily recovered, the Post quotes TSA officials as saying.
The TSA is conducting an internal review of the breach, but remains confident that screening procedures currently in place remain strong, the agency said in a statement.