The NFL is threatening players or teams that take part in fights either before or during games with "significant" punishment, multiple media outlets reported Sunday.

The league sent a memo to all 32 teams last Wednesday after pregame skirmishes occurred in Week 6 between the San Francisco 49ers and Cleveland Browns as well as the Dallas Cowboys and Los Angeles Chargers.

"Sportsmanship and respect are at the core of NFL football, and fighting is irreconcilable with these values," the memo reads, in part. "Fighting is never acceptable, as it risks unnecessary injury to players, coaches, officials, and other game day personnel. These actions send an inappropriate and unacceptable message to players, coaches, and fans at all other levels of the game."

The memo stated that players who fight before or during a game are subject to ejection, suspension and/or a significant fine. In addition, the teams whose players or personnel join an existing fight potentially could be "subject to more significant accountability measures."

The memo also said that teams could be subject to a "forfeiture of draft selections and/or significant fine."

--Field Level Media