DEPARTMENT of Homeland Security documents containing sensitive Super Bowl anti-terrorism information were discovered in the seat-back pocket of a commercial flight.
A CNN employee found the documents, marked "For Official Use Only" and "important for national security" along with the boarding pass and travel itinerary of a scientist in charge of the US government department that conducted anthrax drills ahead of Super Bowl LII in Minneapolis, Minnesota on Sunday (Monday AEST).
The documents included a note that they should be locked up after business hours, shredded prior to being discarded and were intended only for the eyes of those with "an operational need-to-know."
CNN reports the documents, dated December 2017, criticised the planned response to an anthrax attack on the U.S. Bank Stadium in Minneapolis by terrorists, and made recommendations for improvement based on simulation exercises carried out to assess the authorities' ability to respond to a biological attack in a coordinated manner.
CNN said they made the decision not to report on the discovery of the papers until after the game, because Department of Homeland Security officials expressed concern that publishing the news could jeopardise security at the event, attended by more than 73,00 people and watched by an estimated 70 per cent of US households.
The network has also opted not to publish much of the information found in the documents, which could threaten national security.
A DHS official told CNN that the issues in the report had been addressed and that the agency had "great confidence" in its ability to respond to an attack.
Juliette Kayyem, a former DHS official who is now CNN contributor told the network that the report was typical of the kind of reviews carried out before a major event, but revealed a weakness in the Department of Homeland Security.
"The biggest consequence of this mistake may have less to do with terrorists knowing our vulnerabilities and more to do with confidence in the Department of Homeland Security," Kayyem said.
"In the end, confidence in the federal government at a time of crisis is what the American public deserves."
CNN said while they were unable to verify who left the documents on the plane, they were accompanied by the travel itinerary and boarding pass of a Michael V. Walter.
Michael V. Walter is the name of the microbiologist who has been the program manager of BioWatch, the DHS program in charge of anthrax drills in preparation for the Super Bowl, since 2009.
The Philadelphia Eagles defeated the New England Patriots 41- 33, the first Super Bowl win in the team's history.