Up to 100 New Zealand athletes are being investigated for buying and using banned drugs.
Dozens of athletes from a range of sports have been discovered using an online steroid database recovered from a person convicted of selling the substances through a website, the NZ Herald reported.
No All Blacks or Olympians are believed to be involved.
Following the arrest of the steroid website's operator Josh Townshed, it became apparent that athletes were using the website which supplied prescription drugs, including anabolic agents and hormone and metabolic modulators, which are banned in sports.
DFSNZ chief executive Nick Paterson said that proceedings are underway and are being heard individually by the Sports Tribunal and the New Zealand Rugby judicial Committee.
"To have identified approximately 100 athletes using a website selling these substances is extremely disappointing to us at DFSNZ, and should also be of great concern to the wider sporting community," Mr Paterson said.
In the past, anti-doping agencies have typically relied on drug tests to catch out dopers but Mr Paterson says that is no longer the case.
"We have now invested in our intelligence and investigation capability and, coupled with the advances in science, drug cheats are going to find it harder and harder to go under the radar," Mr Peterson said.
Athletes found guilty of doping could be banned altogether from sport.