SHANE Mumford's hopes of a fairytale comeback with Greater Western Sydney could be in jeopardy after a video emerged of the retired ruckman appearing to snort a white powder.

The video was recorded in 2015 according to the Giants, shortly after Mumford suffered a season-ending ankle injury against Collingwood at the MCG in June.

In it, he can be seen sitting in front of a coffee table surrounded by three men. 

The men chant the former Geelong, Sydney and GWS big man's nickname 'Sausage', before the camera pans down to reveal lines of a white substance on the table.

Mumford then snorts one of the lines using what looks to be a rolled-up banknote.

GWS released a statement regarding the video on Tuesday.

"The Giants are aware of an incident, and associated video footage, regarding Shane Mumford from three years ago," it said.

"The club understands the incident took place in 2015 shortly after Shane had suffered a season-ending injury in round 11 that year.

"The club is extremely distressed by the footage and views Shane’s actions as completely counter to the club’s values. 

"The club is disappointed in Shane's choice of actions at this time and also understands that Shane requires a level of medical support with his health and well-being in mind. The club will be working with Shane to ensure he engages in a rehabilitation program along with a range of other measures. 

"Shane has expressed deep remorse, embarrassment and distress in relation to his actions. He understands he has let himself, his family and the club down and caused great embarrassment to those around him. 

"The club has kept the AFL informed of this matter."

In a statement earlier, the AFL said it was also investigating the matter.

Mumford retired at the end of the 2017 season because of a serious foot injury but remained with the club as a ruck coach this year.

While juggling his duties at the Giants, the 2014 club champion took up boxing and won his professional debut in July by TKO.

Earlier this month reports emerged that he was keen to return to the AFL in a playing capacity next year, and with Rory Lobb traded to Fremantle during the NAB AFL Trade Period, Mumford was expected to earn a spot on the GWS list. 

His future is now uncertain on the back of Tuesday's controversy.