By Mark Lamport-Stokes
(Reuters) - The New England Patriots said on Saturday they had followed "every rule to the letter" and accepted no blame for using footballs that were under inflated in their AFC championship win over the Indianapolis Colts six days ago.
The victory earned the Patriots a spot in the Feb. 1 Super Bowl against the defending champion Seattle Seahawks.
The National Football League is investigating why balls used by the Patriots against the Colts were under inflated.
"I believe now 100 percent that I have personally, and we as an organization, have absolutely followed every rule to the letter," Patriots head coach Bill Belichick told a news conference.
"At no time was there any intent -- whatsoever -- to try and compromise the integrity of the game. We try to do everything right and err on caution."
Belichick said he had spent a lot of time this week experimenting with the preparation of footballs for games and had discovered that atmospheric conditions could affect ball pressure.
"When the footballs go out on to the field in the game conditions, whatever those conditions are ... that's where the measurements would possibly be different than what they are in a controlled environment," the coach told reporters.
"We found that once the footballs were on the field for an extended period of time ... they were down approximately 1.5 pounds per square inch. So atmospheric conditions as well as the true equilibrium of the ball are critical to the measurement.
"At no time were any of our footballs prepared anywhere other than in the locker room or in an area very close to that. Never in a heated room or heated condition ... that just didn't happen."
An NFL spokesman said the league would have no comment on Belichick's remarks and declined to say when the NFL investigation would be completed.
The league had said on Friday it would not make any judgments until it concluded the investigation and considered all of the relevant evidence.
Under NFL rules, no alteration of game balls, which must be inflated to between 12.5 and 13.5 pounds per square inch, is allowed once they are approved.
Patriots quarterback Tom Brady threw three touchdown passes during Sunday's game in wet conditions where a firm grip on a slippery ball could have helped.
Both Brady and Belichick have said they knew nothing about the deflated ball issue until Monday.
"Anyone who has seen us practise knows that we make it harder, not easier, to handle the ball," Belichick said on Saturday. "Our players train in conditions that a lot of people would recommend that we not drive in.
"This team was the best team in the AFC during the regular season, we won two games in the playoffs against two good football teams ... the best team in the postseason and that's what this team is."