South Sydney star Cody Walker has been hit with a two-game suspension after he was filmed kicking a man in the chest in a street fight in December.
The former State of Origin five-eighth will miss the first two games of the restarted NRL season and has been fined $15,000 (suspended for 12 months) after the footage appeared on social media this week.
Walker, 30, has five business days to respond but has already indicated he will not appeal any punishment handed down by the NRL's integrity unit.
The NRL has also proposed a $20,000 fine for the club, for failing to promptly disclose the incident to the integrity unit.
South Sydney will also have five days to respond to the breach notice and said in a statement they would consider their position.
Walker was not charged by NSW Police for his role in the incident in Casino in December, which was not reported to authorities at the time.
However he told coach Wayne Bennett, who did not pass on the information.
"The NRL today issued the South Sydney Rabbitohs with a breach notice in relation to an alleged failure to promptly disclose the incident involving Walker," the NRL said in a statement.
"All clubs and club officials have a duty to report any incident which may lead to a breach of NRL rules, including suspected breaches, and NRL clubs are responsible for ensuring compliance."
The NRL only became aware of the incident this week after Walker made a report to police over an alleged blackmail attempt for $20,000.
It is claimed there were threats to sell the video to media before it was then released online.
The Rabbitohs will be without Walker to restart their season against arch rivals Sydney Roosters on Friday night as well as a trip to Melbourne in round four.
It opens the door for rookie Troy Dargan to make his NRL debut in the halves alongside Adam Reynolds.
The club is also waiting for confirmation from the NRL's biosecurity expert that James Roberts can return to the squad after he was released from a rehabilitation clinic on Thursday.
Roberts could be forced to undergo a 14-day quarantine before rejoining the Rabbitohs' bubble, but the club is hopeful of having him available to play the Roosters.
Meanwhile, the NRL has upheld fines and suspended bans for Latrell Mitchell, Josh Addo-Carr and Tyrone Roberts-Davis for failing to comply with social distancing laws last month.