An offensive banner unveiled by Western Sydney Wanderers supporters during Saturday night's derby could land the club in hot water after Football Federation Australia launched an investigation into the "unacceptable" mural.

A tifo was raised in the home end depicting a Sky Blue face performing a sex act minutes before full-time in their 1-0 win on Saturday night. The image was widely interpreted as a homophobic insult and was met with an immediate backlash from the governing body, who have not ruled out disciplinary consequences for the club or its supporters.

"FFA is aware of the unauthorised and totally unacceptable banner that was displayed in the Western Sydney Wanderers area during Saturday night's Sydney Derby at ANZ Stadium," A-League boss Greg O'Rourke said.

"The discriminatory nature of the 'tifo' has no place in society and will not be tolerated in the A-League. We are working with the club and currently gathering as much information as possible and will deal with the matter when we have all available facts including CCTV footage."