Russia's anti-doping agency says discus thrower Darya Pishchalnikova has been provisionally suspended by the IAAF after a positive doping test that could cost her the silver medal from the London Olympics.

RUSADA says the world governing body has suspended Pishchalnikova from Oct. 31 until a final ruling in the case.

Pishchalnikova tested positive for the banned substance Oxandrolone in a reanalysis of a sample taken in an out-of-competition control last May. The original test was negative, but her sample was checked again months later based on a more advanced testing method introduced by the World Anti-Doping Agency.

The positive test means Pishchalnikova could be retroactively disqualified from the London Games, where she finished second behind Croatia's Sandra Perkovic.