Lyudmila Blonska, the Ukrainian athlete who won silver in the women's heptathlon, is facing disciplinary action after failing a drugs test. It is understood Blonska, who has already previously served a two-year ban for drugs, tested positive for an anabolic steroid.
The case is expected to come before the IOC's disciplinary commission and executive board, which meet tomorrow.
After Blonska's silver medal Britain's Kelly Sotherton, who finished fifth in the event, called for a worldwide policy to prevent drug cheats from returning to compete in the Olympics.
The IOC refused to confirm the positive finding, saying in a statement: "The IOC does not comment, or provide information, on any doping cases until a decision is made by either the disciplinary commission or executive board."