Officials say two Australian Rules football clubs and a number of rugby league teams are being probed for the use of banned performance-enhancing drugs.
Federal justice minister Jason Clare, criticised for releasing a damning report into doping in Australian sports last week that lacked details, confirmed that a number of clubs in the competing football codes were under suspicion.
Mr Clare said authorities had passed on the names of the clubs to both of the sport's governing bodies, and they will tell the clubs concerned.
Reuters reports that the Melbourne-based Essendon Bombers is known to be one of the AFL clubs.
The NRL confirmed that multiple clubs were under suspicion, but would not inform them for 24 to 48 hours, for legal reasons.
Gillard says clubs should come clean
Australian Prime Minister Julia Gillard says football clubs should come clean to their fans about any drug use by their players.
The Australian Crime Commission has uncovered doping in professional sport, along with possible match-fixing and manipulation of betting markets.
AAP reports police, the Australian Sports Anti-Doping Authority, the AFL and NRL are investigating.
Ms Gillard said fans were anxious to know about the circumstances of their own club.
"So I would say to clubs, please come clean. Make sure that you tell your fans what is going on," the prime minister said in Queenstown, New Zealand.
"For clubs who have absolutely nothing to hide then it will come as a great relief to fans to know that.
"For clubs who have had problems, then it's better off to step forward and be very clear about that."