The Storm warned on Tuesday that the star playmaker was on his last chance after post-season video emerged of him partying with a white powder.

Munster, as well as Storm teammates Brandon Smith and Chris Lewis, were sanctioned by the NRL for their antics following their finals exit.

Issued with NRL breach notices on Tuesday alleging they brought the game into disrepute, the trio will miss the 2022 season opener and face various fines, with Munster hardest hit with a $30,000 penalty.

Warriors teenager Reece Walsh faces a two-game ban and a $5000 fine after his Gold Coast arrest which has led to a drug investigation.

Accepting the sanctions, the Melbourne players read statements to the media on Tuesday with Munster admitting he had had a "difficult relationship" with alcohol.

"I thought I'd dealt with this issue but clearly I still have some hurdles to overcome," said Munster, who is due to become a father in December.

"I made the decision in consultation with the club doctor to seek some help with this battle.

"Starting tomorrow, I'll be attending a treatment facility for the next four weeks.

"I know I've let a lot of people down ... hopefully you'll see by my actions that I'm dedicated to change."

Storm boss Justin Rodski said his players hadn't admitted taking any drugs and the NRL was unable to test them for illicit substances in the off-season.

"The findings from the NRL integrity unit haven't produced any evidence to suggest what was in the video," Rodski said.

"Through excessive consumption of alcohol and intoxication the players have limited memory of what did or didn't take place in that hotel room.

He defended the lightweight one-game bans and said the "totality of sanctions and penalties handed down across the NRL and the club were significant and serious".

Melbourne have also put Munster on a 12-month booze ban, fined him $100,000 fully suspended and axed him from the leadership group.

Rodski said if the representative five-eighth breached the alcohol ban he would cop the hefty fine and face the Storm's board which would decide his fate.

Asked if the 27-year-old was on his last chance after previous disciplinary issues Rodski replied: "I think you could take from this that he is, yes."

The Storm chief executive said it was "premature" to discuss letting Munster walk at the end of 2022 to join the expansion club in Brisbane.

New Zealand international Smith revealed his family had been targeted on social media platforms since the video.

"I know I have let a lot of people down, especially my family," Smith said.

"I'm sorry for all the criticism you guys have received over social media platforms, which is probably the most painful and heartbreaking thing I've had to deal with."

NRL boss Andrew Abdo said the four players, who would also undergo education and training, had let the rugby league community down.

Australian Associated Press