NFL investigators met Tuesday with Patriots officials to determine whether footballs used in New England’s 45-7 victory against the Indianapolis Colts in the AFC championship game were not properly inflated, according to a person familiar with the league’s handling of the situation.

And while the league indicated it may wrap up its investigation by week’s end, ESPN reported late Tuesday night that 11 of the 12 footballs that were used by the Patriots were under-inflated.

An NFL spokesman, Michael Signora, said the league had “no comment at this time” about the report, which stated that the footballs were under-inflated by 2 pounds per square inch.

Under NFL rules, game balls must be inflated to between 12.5-13.5 PSI. In-game officials inspect footballs two hours before kickoff and only give the balls to the respective teams 15 minutes before kickoff.

Troy Vincent, the NFL’s executive vice president for football operations, told The Associated Press that the league’s “investigation is currently under way and we’re still awaiting findings.”

Vincent said on NBC radio that the investigation could be concluded by the end of this week. Another person familiar with the investigation said the league might make a statement by the end of the week, but the timing of any potential discipline is uncertain.

The NFL Game Operations Manual stipulates that anyone who alters the inflation of a ball faces a $25,000 fine. But the language indicates additional penalties could be imposed.

Coach Bill Belichick, who said Monday he would cooperate with the probe, said that he wasn’t aware of the issue until early Monday morning.

“We’re hoping to wrap that up in the next two or three days,” Vincent said of the investigation. He didn’t say when any punishment might be imposed if it is determined that the Patriots violated the league’s rules.

Using under-inflated footballs can help quarterbacks and receivers grip the ball better, especially in the rain. It rained during Sunday night’s game.

The result of the game counts, and the Patriots will play the Seahawks in the Super Bowl on Feb. 1 at University of Phoenix Stadium.

If the NFL finds the Patriots illegally used under-inflated footballs, the league could fine the team and/or remove draft picks.

While the focus of the investigation is on the footballs used in Sunday’s game, it is uncertain if the NFL will look to see if the Patriots may have under-inflated football in previous games.

According to a source, after Colts linebacker D’Qwell Jackson intercepted Tom Brady in the second quarter, Jackson gave the ball to a Colts equipment staffer, who noticed the ball seemed under-inflated and informed Coach Chuck Pagano.

General Manager Ryan Grigson was called in the press box, and he contacted the NFL vice president of game operations, Mike Kensil. The officials then were notified of the possibility of the Patriots using balls that were not properly inflated.

A person familiar with the investigation said that ball, as well as several others from the game, were removed from play because of suspicions that they were underinflated.

Belichick would not say whether the league had contacted the team. “Any questions on that, you should talk to (the league) about that,” Belichick said at a news conference. He was not asked any additional questions on the matter.

This is not the first time the Patriots have been involved in a game-day controversy.

In a 2007 game against the Jets, the Patriots were accused of illegally taping the Jets’ defensive signals on the sideline. The NFL investigated and determined the Patriots had violated NFL rules and forced them to surrender their 2008 first-round pick. The team was fined $250,000 and Belichick was fined $500,000.

The Patriots qualified for the Super Bowl that season, becoming the first NFL team to go 16-0 in the regular season. They lost to the Giants in the Super Bowl at the same stadium in which they will face Seattle.