Canterbury have informed the NRL's integrity unit of a video being circulated involving star second-rower Adam Elliott.
The video is believed to have only surfaced recently, but the club say it was filmed five years ago at a private event.
"The Canterbury Bankstown Bulldogs would like to confirm that they are aware of a video having surfaced involving Adam Elliott," the club said in a statement.
"The video relates to something that was filmed at a private gathering five years ago.
"The club has informed the NRL Integrity Unit of the matter."
The timing of the video is suspect in that Elliott is currently off contract and details of negotiations have been reported in recent days.
Any scandal could have the potential to drive the 25-year-old's price down.
The Bulldogs were faced with a similar issue in last year's pre-season, when videos of Dylan Napa surfaced.
At the time, the NRL determined they would not punish any players for videos recorded before that point if they contained no illegal behaviour.
That decision was made with a view to protect players from being extorted.
Australian Associated Press