On Monday, former U.S. District Judge Sue L. Robinson said Watson had violated the league's policy after more than 20 women accused him of sexual misconduct and abuse, calling his behavior "egregious" and "predatory."

Prior to the ruling, the league had sought an indefinite suspension of at least one year. Robinson had based the duration of six weeks on previous NFL suspensions.

"The NFL notified the NFLPA that it will appeal Judge Robinson's disciplinary decision and filed its brief this afternoon," a spokesman for the NFL told Reuters in a statement.

Under the appeal process, three outside experts will make recommendations to NFL Commissioner Roger Goodell or his designee, and either Goodell or the designee will make the final decision on the length of the suspension, meaning it will likely increase.

The NFL Players Association may choose to challenge the appeal ruling in federal court, which could lead to a protracted legal battle. The NFLPA and Watson both have two days to respond to the appeal.

All but four of the 24 lawsuits that alleged sexual assault by Watson were settled in June after more than 20 women came forward last year.

A Texas grand jury previously declined to indict Watson.

In March, the 26-year-old denied sexually assaulting or acting in an inappropriate manner towards any of the 22 women who had made complaints against him at the time.

Watson, who did not play last season, joined the Browns from the Houston Texans in March this year, signing a five-year, $230million contract.