Olympic 1,500-meter champion Asli Cakir Alptekin of Turkey was charged with doping and could be stripped of her gold medal. Another female Turkish athlete, hurdler Nevin Yanit, also was charged with doping violations and could lose her European indoor title.
Alptekin had abnormal blood values in her biological passport, IAAF spokesman Nick Davies told The Associated Press on Friday. The passport system tracks variations in an athlete's blood profile over time for signs of cheating.
Yanit, meanwhile, had "multiple positive findings following target tests carried out in-competition and out-of-competition" by track and field's governing body, Davies said.
Both cases have been referred to the Turkish athletic federation. Pending a verdict, both athletes are suspended and ineligible to compete.
"If they are convicted, they will be stripped of those medals," Davies said. "For now though, they are just stopped from running until the legal process is completed."
Alptekin also could face a life ban for a second offense. She served a two-year suspension for doping after the 2004 world junior championships.
Alptekin finished ahead of teammate Gamze Bulut to win the gold medal in London in 4 minutes, 10.23 seconds. If Alptekin is stripped of the victory, Bulut would stand to be upgraded to the gold. Maryam Yusuf Jamal of Bahrain was third and Tatyana Tomashova of Russia fourth.
Yanit, a two-time European champion in the outdoor 100-meter hurdles, won the 60-meter hurdles gold at the European indoors in Goteborg, Sweden, in March in 7.89 seconds. Alina Talay of Belarus was second, followed by Veronica Borsi of Italy and Derval Orourke of Ireland.
Yanit finished fifth in the London Olympics final in the 100 hurdles.
The doping scandal comes as Istanbul is bidding for the 2020 Olympics, competing against Tokyo and Madrid. The International Olympic Committee will select the host city on Sept. 7.
Ugur Erdener, president of the Turkish Olympic Committee, said the IOC can be "totally assured" of the country's adherence to World Anti-Doping Agency rules.
"We fully support all authorities in this ongoing investigation," Erdener said. "Doping is a major global issue. Turkey is ready to fulfill its responsibilities in helping to eradicate it from world sport.
"Any athlete found to have cheated will be punished to the full extent of Turkey's comprehensive and rigorously enforced anti-doping legislation, other laws and in accordance with international anti-doping practices."