The World Anti-Doping Agency (Wada) may appeal to the Court of Arbitration for Sport (CAS) after Chinese swimming star Sun Yang served a three-month doping ban in secret, a spokesman told AFP.
The World Anti-Doping Code says drug violations must be made public within 20 days.
Chinese officials have denied covering up the suspension of the two-time Olympic champion, which took place between May and August, but was announced only on Monday.
"Wada has not yet received the full decision regarding this case," the spokesman told AFP. "Once it is received, Wada will review the reasons for the decision and will subsequently decide whether or not to use its independent right of appeal to the CAS."
Section 14.2.2 of the World Anti-Doping Code says violations must be publicly reported within 20 days and that decisions have to be sent to Wada in the same time period.
Sun, the 1,500m world record holder, received his suspension in July, but it was backdated to May, when he tested positive at China's national championships.
The swimmer, who also has five world titles to his name, completed the ban on Aug 17 and, in September, won three golds at the Asian Games.