Reporters have discovered sensitive anti-terrorism plans for the Super Bowl marked “for official use only” in the seat pocket of a commercial airline.

The documents, which came from the Department of Homeland Security’s (DHS) BioWatch programme, were meant to be kept locked up during business hours and shredded before being thrown away. But there they were, sitting in a seat back pocket when a CNN reporter got on the plane before Sunday's game.

Alongside the documents were the boarding pass and flight itinerary of Michael V Walter, CNN reported. According to a Congressional biography, Mr Walter has been the BioWatch programme manager since 2009.

A DHS official told CNN that the documents were the subject of an "operational review" and that "DHS does not comment on personnel matters or potential pending personnel action”.

The BioWatch programme is responsible for providing early detection of bioterrorism attacks, and helping communities prepare for such events. The documents discovered in the seat pocket included a review of two exercises that BioWatch conducted to assess whether local emergency response agencies were prepared for a possible anthrax attack at Super Bowl LII in Minneapolis, according to CNN.

The ten best Super Bowls Show all 10 1 /10 The ten best Super Bowls The ten best Super Bowls GETTY IMAGES The ten best Super Bowls Super Bowl XXXIV (January 2000)

St. Louis Rams 23 - 16 Tennessee Titans

Atlanta, Georgia

The Rams' domination of the opening three quarters was reflected by 16 unanswered points on the scoreboard. The Titans responded by staging the biggest Super Bowl comeback ever seen to tie the game at 16-16 with 2:12 left. Quarterback Kurt Warner (centre) snapped the Rams out of their complacency and on the next drive scorched a 73-yard touchdown pass to Isaac Bruce. The ding-dong-ding battle remarkably had one final dong left; with less than six seconds to go the Titans' Kevin Dyson was dumped one agonising yard short of a game-tying touchdown, in a play now known simply as "The Tackle". GETTY IMAGES The ten best Super Bowls Super Bowl XXXVIII (February 2004)

Carolina Panthers 29 - 32 New England Patriots

Houston, Texas

Three first half minutes remained and the game was still scoreless - the longest a Super Bowl had ever gone without a point being scored - when the Patriots' Deion Branch caught a five-yard Tom Brady touchdown pass to break the deadlock. Cue offensive mayhem and three minutes later Janet Jackson's nipple interrupted the game with New England up 14-10. A scoreless third quarter was the calm before the tornado, over the 15 minutes of the last quarter the two offensives combined to share a record 37 points. With just four seconds left the scores were tied at 29-29 when Adam Vinatieri won the game for the Patriots with a 41-yard field goal (pictured). GETTY IMAGES The ten best Super Bowls Super Bowl XXIII (January 1989)

Cincinnati Bengals 16 - 20 San Francisco 49ers

Miami, Florida

The 49ers fourth-quarter game-winning drive has gone down in the game's annals and played a big part in the creation of quarterback Joe Montana's legend (pictured). Trailing 16-13 and up against the league's top-rated quarterback in Boomer Esiason, "Joe Cool" got the ball back under his command on his own 8-yard line with just 188 seconds to make 92-yards. Montana needed only 154 of those to land the ball in John Taylor's endzone-dwelling hands. GETTY IMAGES The ten best Super Bowls Super Bowl XIII (January 1979)

Pittsburgh Steelers 35 - 31 Dallas Cowboys

Miami, Florida

The first Super Bowl rematch had everything required of a classic: nerve-induced fumbles, controversial calls, high-scoring losers, touchdown passes that spun three-quarters the length of the field and a rousing but futile comeback. Just like three years earlier, the Steelers held off a late Cowboys rally to be crowned champions. A remarkable nine players on the field ended up in the Hall of Fame. GETTY IMAGES The ten best Super Bowls Super Bowl X (January 1976)

Dallas Cowboys 17 - 21 Pittsburgh Steelers

Miami, Florida

This was the appetiser for what was to come at Super Bowl XIII but deserves to be considered a classic in its own right. The Steelers were leading 15-10 deep into the final quarter when quarterback Terry Bradshaw (pictured) threw one of the most audacious touchdown passes. And he had no idea the play was completed. A split second before being blitzed by two Cowboy defensemen Bradshaw released a 64-yard pass, as the ball dropped safely into Lynn Swann's hands; the game-winning QB was knocked out cold on the turf. GETTY IMAGES The ten best Super Bowls Super Bowl XXV (January 1991)

Buffalo Bills 19 - 20 New York Giants

Tampa, Florida

This was a contest between the brutal defensive brawn of the Giants and the more ostentatious 'no-huddle' offense of the Bills but will always be remembered for the last three seconds of the game. The free-scoring Bills were largely contained by Giants defensive co-ordinator Bill Belichick's game plan but with three to go they secured field goal position for their kicker Scott Norwood. The 74,000 crowd held its breath as Norwood's kick (pictured) sailed wide right and with it the Super Bowl. Belickick's game plan now resides in the Hall of Fame. GETTY IMAGES The ten best Super Bowls Super Bowl XXXVI (February 2002)

St. Louis Rams 17 - 20 New England Patriots

New Orleans, Louisiana

The Patriots were led by replacement second-year quarterback Tom Brady and no one gave them a chance against an offense nicknamed "The Greatest Show on Turf". The Rams showed they also had guts in abundance, after slipping to a 17-3 deficit late in the third-quarter they rallied to tie the game when Kurt Wanrer threw a 26-yard touchdown completion pass with 1:30 left on the clock. However, just as he would two years later, the Patriots Adam Vinatieri struck a last-second field goal to stave off the first ever Super Bowl overtime. GETTY IMAGES The ten best Super Bowls Super Bowl XXI (January 1987)

Denver Broncos 20 - 39 New York Giants

Pasadena, California

It wasn't the drama or tightness of the game that made this a Super Bowl to remember; instead it was a demonstration of the supreme control a quarterback can exert over the field of play. All the talk beforehand was on the edge-of-the-seat improvisations of Bronco's John Elway but by the time the clock had run down on the final quarter the name on everybody's lips was New York's Phil Simms. He completed a Super Bowl record 22 out of 25 pass attempts and also gained 25-yards on three rushing plays to dominate the game and capture the Super Bowl. GETTY IMAGES The ten best Super Bowls Super Bowl III (January 1969)

New York Jets 16 - 7 Baltimore Colts

Miami, Florida

A classic game it was not but in terms of historical significance it may just be the most important of all. It was the first to officially bear the name "Super Bowl" and has gone down as one of the biggest upsets in American sports history. After the two rival football league's had agreed to merge it was felt the new league would be forever dominated by National Football League teams, who had already won the first two contests. Instead, America woke up to the potential of the American Football League as the Jets quarterback, Joe Namath (pictured), backed up his bold pre-game prediction and, despite not throwing a touchdown pass in the game or any passes at all in the fourth quarter, guided the Jets to victory.

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The exercises, conducted in June and November of last year, showed that "some local law enforcement and emergency management agencies possess only a cursory knowledge of the BioWatch program and its mission,” according to the report. They also showed that some health agencies were confused by the warnings issued during the drill, and didn’t know who they could safely share information with during an emergency.

This "made it difficult for them to assess whether their city was at risk," and "creates a situation where local officials are deciding on courses of action from limited points of view,” the documents said, according to CNN.

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DHS Press Secretary Tyler Q Houlton said in a statement that the agency had worked for two years to prepare local and federal law enforcement for Sunday’s Super Bowl. He noted that these preparations often involved testing emergency preparedness, and called the BioWatch exercises a “resounding success”.

The DHS did not respond to questions about whether the issues laid out in the report had been resolved before the game.