New England Patriots quarterback Tom Brady damaged "the integrity" of American Football and attempted to hide evidence during the 'Deflate-gate' investigation, the National Football League has said.
The Patriots deflated balls to give themselves an advantage during January's 45-7 AFC Championship over the Indianapolis Colts in Boston which sent them to the Super Bowl.
Brady, 37, was found earlier this year to be "at least generally aware of inappropriate activities" and handed a four-match ban, which was upheld on Tuesday.
|What is Deflate-gate?|
|Read more background to this story here|
The 20-page statement said Brady testified that it is his "ordinary practice" to destroy his mobile phone and Sim cards when he gets a new phone.
Brady said during the appeal hearing that he gave his old phone to his assistant to be destroyed on or about 6 March 2015 - the day he met with NFL investigators.
The NFL statement said: "He [Brady] did so even though he was aware that the investigators had requested access to text messages and other electronic information that had been stored on that phone.
"During the four months that the cell phone was in use, Brady had exchanged nearly 10,000 text messages, none of which can now be retrieved from that device."
According to reports, 11 of the 12 game balls the Patriots provided were under-inflated by about two pounds per square inch, giving Brady more grip in the cold and wet conditions.
NFL commissioner Roger Goodell said: "I find that, with respect to the game balls used in the AFC Championship game and the subsequent investigation, Mr Brady engaged in conduct detrimental to the integrity of, and public confidence in, the game of professional football."
Brady is considered to be one of the greatest quarterbacks of all time, winning the Super Bowl Most Valuable Player award three times.
He will now miss a quarter of the upcoming regular season, and is scheduled to make his return against the Colts on 18 October.
|Did deflating balls make a difference?|
|"They could have played with soap for balls and beat us," tweeted Colts tight end Dwayne Allen at the time. "Simply the better team."|
|The Patriots scored 17 points in the first half against Indianapolis, when the balls were below their optimum pressure.|
|After the interval, when the balls had been re-inflated, they scored 28.|
Brady, who denies being involved in any scheme to tamper with balls, could take the case to a federal court in a bid to overturn the suspension.
In a statement on Tuesday, Patriots said they "cannot comprehend" the NFL's position and claimed the league "has no hard evidence of wrongdoing".
They accused the league of "attempting to destroy the reputation of one of its greatest players and representatives" and added: "We continue to unequivocally believe in and support Tom Brady."
And the NFL Players Association said it would appeal "this outrageous decision" on behalf of Brady, describing the ban as a "new low" based on a "smokescreen of irrelevant text messages".
Locker room attendant Jim McNally and equipment assistant John Jastremski exchanged colourful text messages which implied the pair worked together to deflate match balls, the NFL said in its report in May.
In the messages McNally described himself as "the deflator" and revealed requests to Brady for cash, shoes and signed footballs.
McNally and Jastremski were indefinitely suspended by the Patriots. The report absolved other Patriots players and staff, as well as all coaches, including head coach Bill Belichick, and the team ownership.
Brady will not receive any pay during his ban, while the Patriots were fined $1m and forced to forfeit a 2016 first-round draft pick.