New England Patriots head coach Bill Belichick has revealed that he has "no explanation" as to why the footballs his team were using in the AFC championship game were below the NFL PSI requirement.

The NFL announced that it was investigating the incident in the AFC title game after Indianapolis Colts linebacker D'Qwell Jackson brought a ball he had intercepted from Tom Brady to the sideline and informed his coaches that he felt it was under-inflated.

Following the investigation a report suggested that 11 of the 12 balls used by the Patriots were not at the required PSI level, which has shocked Belichick who has insisted that he has no idea how that would be the case for his team.

Belichick told reporters: "I can tell you that in my entire coaching career, I have never talked to any player, staff member about football air pressure. That is not a subject that I have ever brought up. To me, the footballs are approved by the league and officials pregame, and we play with what's out there. That's the only way that I have ever thought about that.

"The National Football League is investigating this situation. We have cooperated fully, quickly and completely with every request they have made, and continue to be cooperative in any way that we can. I have no explanation for what happened, and that's what they're looking into."

The Patriots face the Seattle Seahawks in the Super Bowl on February 1 at Glendale.