The largest U.S. youth football program has instituted strict new regulations aimed at better protecting players from concussions and other head injuries, according the a report by NBC News on Tuesday.

Pop Warner, a nonprofit organization with football and cheerleading programs, is rolling out the new regulations amid growing concern about concussions at all levels of football. Some 2,000 former NFL players sued the league last week alleging it concealed the risk of brain injury from players.

Pop Warner's new rules would closely regulate contact during practice, which accounts for more head injuries than games, according the NBC's report.

It said most Pop Warner teams practice nine hours a week, and under the new guidelines only a third of that time could be spent in contact with another player. In addition, no head-to-head hits would be allowed and tackling could only be initiated within a three foot zone during practice.

NBC said there are more than 4 million concussions in sports and other recreational activities each year in the United States each year. Football accounts for more than half of those.

(Reporting by Paul Thomasch)