The Storm confirmed on Tuesday the trio had "cooperated fully" with the investigation, while the NRL club will also conduct its own probe into the matter.

Two undated videos surfaced online, the first on Monday evening, which appear to have been recorded after Melbourne's NRL preliminary-final loss to Penrith.

The initial vision, seen by AAP, appears to show Munster, Smith and several other people in a room with a white substance on a table.

A second video shows Munster dancing on the same table.

Lewis, who played 20 games this season after making his debut as a 28-year-old last year, wasn't visible but the Storm later confirmed he was also interviewed.

Storm boss Justin Rodski said the club was very disappointed and was taking the matter "extremely seriously".

"The players involved have fully cooperated with the NRL and the NRL Integrity Unit investigation," Rodski said in a statement.

"It is our understanding this investigation is unlikely to be concluded this week.

"Melbourne Storm unashamedly sets high standards and makes no apologies for protecting and upholding the professionalism and values of our organisation.

"The club is conducting its own investigation into the matter and will provide an update on our findings in conjunction with the NRL when both processes have concluded."

Rodski said no further comment would be made until then.

Australian Associated Press