BOSTON (CBS) – The NFL has found that 11 of the 12 game balls used by the Patriots during Sunday’s AFC Championship were under-inflated, ESPN’s Chris Mortensen reported.

League sources told Mortensen that the balls were under-inflated by two pounds per square inch of air less than what’s required by NFL regulations.

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It is unclear how the balls became under-inflated and the league has not commented on the report.

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The Patriots defeated the Colts 45-7 in Sunday night’s AFC Championship Game at Gillette Stadium. In rainy conditions, Tom Brady threw for 226 yards, three touchdowns and one interception, while LeGarrette Blount rushed for 148 yards and three touchdowns.

Patriots running back LeGarrette Blount ran for 148 yards and 3 TDs against Indy in the AFC Championship Game. (Photo by Maddie Meyer/Getty Images)

Patriots running back LeGarrette Blount ran for 148 yards and 3 TDs against Indy in the AFC Championship Game. (Photo by Maddie Meyer/Getty Images)

WTHR’s Bob Kravitz reported after the game that the NFL would investigate whether the Patriots used footballs that were not inflated under the guidelines of the NFL rules. That report was later confirmed, prompting Bill Belichick to be asked about the situation on Monday afternoon.

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“We’ll cooperate fully with whatever the league wants us to [do], whatever questions they ask us,” Belichick said. “I didn’t know anything about it until [Monday] morning.”

New York Newsday reported Tuesday that the Colts first noticed something unusual after linebacker D’Qwell Jackson intercepted Brady in the second quarter.

D'Qwell Jackson intercepts a pass intended for Rob Gronkowski in the second quarter of the 2015 AFC Championship on January 18, 2015. (Photo by Al Bello/Getty Images)

D’Qwell Jackson intercepts a pass intended for Rob Gronkowski in the second quarter of the 2015 AFC Championship on January 18, 2015. (Photo by Al Bello/Getty Images)

Jackson reportedly gave the ball to someone on the equipment staff, who thought it seemed under-inflated. He allegedly told Colts coach Chuck Pagano. The Colts general manager was also notified and he notified a league official, according to the report.

CBS Sports.com reported late Tuesday night that some of the Baltimore Ravens believe kicking balls used in their playoff loss in Foxboro on January 10 “were slightly under-inflated, according to league sources.”

There has been no official comment from the NFL.

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The Patriots will face the Seahawks in Super Bowl XLIX on Feb. 1 in Arizona.