The Olympics have been hit by a fourth doping case after Ukrainian cross country skier Marina Lisogor tested positive for the banned substance trimetazidine.
The Ukrainian Olympic Committee said Lisogor, 30, told a disciplinary hearing that she had unwittingly consumed the substance in a medicine.
The case came a day after news of failed tests for German biathlete Evi Sachenbacher-Stehle and Italian bobsledder William Frullani.
The Latvian men's ice hockey player Vitalijs Pavlovs has also been sanctioned for failing a drugs test.
