Melbourne Storm coach Craig Bellamy admits Cameron Munster has an uneasy relationship with alcohol as the club locks fellow boom youngster Curtis Scott into its long-term plans with an extension until the end of 2021.

The spotlight has been on Munster's future and off-field behaviour for some time, with NRL.com revealing on Wednesday that senior Storm figures have grown weary of the 23-year-old's antics, most notably a scuffle with teammate Ben Hunt while on Kangaroos duty at the World Cup.

Melbourne have strongly denied any suggestion Munster could be released before his current contract expires at the end of 2019, however Bellamy concedes the Queensland and Australian rep needs to change his behaviour when he drinks alcohol.

"Deep down he's a really good kid. I think everyone really likes him," Bellamy told Channel 7.

"Early he had some rough edges we had to fold off a touch. Following that World Cup he just seemed to lose his way there for a little bit.

"At times, he has some issues every now and then when he drinks alcohol. He needs to temper that and understand how much he can drink or can't drink so he doesn't do silly things.

"He just needs to behave himself off the field and be consistent about it."

As one of the hottest young playmakers in the game, Munster could fetch up to $1 million on the open market.

However sources close to the Rockhampton junior stress that Melbourne is the best place for Munster to realise his undoubted potential, with both parties committed to getting him back on track and keeping him there.

As for Scott, he will form another key pillar of the Storm's ongoing succession planning for life after the Big Three with his latest three-year extension reportedly valued at $1.5 million.

The 20-year-old joins the likes of Brodie Croft (2020) and Brandon Smith (2022) in committing to the club for the long haul, as stalwarts Cameron Smith and Billy Slater enter the twilight of their careers.

As a high school prodigy Scott had up to a dozen NRL suitors chasing his signature, but during his most recent negotiations never seriously entertained leaving the 2017 premiers.

"We are delighted Curtis has chosen to continue his career with us in Melbourne," Storm Football Director Frank Ponissi said.

"He has shown over his first two seasons that he has the ability to play at NRL level and the challenge is now for him to continue to improve. We are looking forward to helping Curtis reach his full potential at Storm.

"It is fantastic our young talent are committing to the club for the long-term, our members and fans have reason to be excited."