Olympic silver medalist Darya Pishchalnikova is under investigation by the sport's world governing body (IAAF) after failing a drugs test, the Russian anti-doping agency (RUSADA) said.
Pishchalnikova, who finished second at the London Olympics this year, tested positive for an anabolic steroid.
"In October 2012, the World Anti-Doping Agency (WADA) ordered that Pishchalnikova's sample, taken on May 20 2012, was re-tested at a laboratory in Lausanne. The result was adverse," RUSADA said in a statement on its website.
Pishchalnikova, who has denied any wrongdoing, could face a life ban from the sport if found guilty because it would be her second offence. She served a doping ban of two years nine months from July 2008 to April 2011.