FOXBOROUGH, Mass. (AP) — Patriots coach Bill Belichick said Thursday he doesn't know how footballs became deflated during the game that got his team to the Super Bowl.

But Belichick declined to answer questions after saying he knew nothing until Monday morning about accusations that his team cheated with underinflated footballs in its win against the Colts in the AFC championship game on Sunday night.

The NFL is investigating. Belichick said the team is fully cooperating.

"I had no knowledge of this situation until Monday morning," said Belichick, who said he was "shocked" to learn the news.

"I would say I've learned a lot more about this process in the last three days than I knew or have talked about it in the last 40 years that I've coached in this league," Belichick said during an 8 1/2-minute opening statement during an 11 1/2-minute news conference. "I had no knowledge of the various steps involved in the game balls and process that went through."

Belichick did not specify who in the Patriots organization was responsible for the underinflated balls, or absolve anyone besides himself of potential wrongdoing.

Softer balls are generally considered easier to throw and catch, and quarterbacks, specialists and equipment managers are known to have very individualized preferences in how footballs are readied for games. Belichick said he was unaware of the process for game balls until the accusations were raised.

Belichick said he sometimes hears quarterbacks, kickers and other specialists talk about their preferences.

"I can tell you and they will tell you that there is never any sympathy from me whatsoever on that subject. Zero," Belichick said.

Patriots quarterback Tom Brady is expected to address reporters later Thursday.

"Tom's personal preferences on his ball, footballs, are something that he can talk about in much better detail and information than I could possibly provide," Belichick said. "I can tell you that in my entire coaching career I have never talked to any player, staff member about football air pressure."

The NFL requires balls to be inflated between 12.5 and 13.5 pound per square inch. Under league rules, each team provides 12 balls for use on offense. Referees approve the balls more than 2 hours before game time, then keep the balls until they're turned over to ball handlers provided by home teams just before kickoff.

Belichick said the balls used by the Patriots offense are inflated to the "12 1/2-pound range" and "any deflation would then take us under that."

Going forward, he said, the Patriots will inflate footballs to a safe level to prevent them from dropping under allowable air pressure during games.

"We will take steps in the future to make sure that we don't put ourselves in this type of situation again," he said.

The coach who has won three Super Bowls said he generally forces players to practice under bad-ball conditions.

"Anytime players complain about the quality of the footballs, I make it worse and that stops the complaints," he said. "We never use the condition of the footballs as an excuse. We play with whatever or kick with whatever we have to use."

The issue has drawn strong reaction from around the game and its fans as the Patriots prepare to play the Seattle Seahawks on Feb. 1 in Glendale, Arizona, for the NFL title.

Several players said it would not distract them in preparing for the game.

"It's unfortunate. We'd rather be celebrating our trip to the Super Bowl," special teams captain Matthew Slater said. "It's important to us that we respect the game and deal with things in a way that's considered professional."

Belichick declined to answer several questions after his opening remarks, answering several of them by saying: "I've told you everything I know," and "I don't have an explanation."

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