"The International Olympic Committee's Disciplinary Commission officially informed Ukrainian NOC today that Ukrainian cross-country skier Marina Lisogor was tested positive for the substance trimetazidine included into the forbidden substances' list since January 1st, 2014," the Committee said in a statement.
"Marina Lisogor gave her explanation at the Disciplinary Commission meeting that she took the drug product 'Preductal' not knowing that it consists the forbidden ingredient, thus unintentionally breaking the IOC anti-doping rules."
Lisogor and Kateryna Serdyuk had pulled out the women's team sprint on Wednesday with the Ukrainian delegation citing a back injury affecting Serdyuk.
Ukraine's Olympic Committee did not say whether Lisogor had failed her doping test at the Sochi Games.
On Friday, it was revealed German biathlete Evi Sachenbacher-Stehle and Italian bobsledder William Frullani had both failed dope tests.