Ukrainian cross-country skier Marina Lisogor has tested positive for the banned substance trimetazidine, the Ukrainian Olympic Committee announced on Saturday.
Lisogor, 30, finished 58th in the ladies sprint free qualification race on February 11 at the Sochi Winter Olympics.
A Ukrainian Olympic Committee statement read: "The International Olympic Committee's disciplinary commission officially informed the Ukrainian NOC today that Ukrainian cross country skier Marina Lisogor was tested positive for the substance trimetazidine included in the forbidden substances list since January 1, 2014.
"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.
"The decision regarding Maryna Lisogor will be made in accordance with IOC regulations."
News of Lisogor's failed test followed on from Friday's announcements regarding Germany's two-time winter Olympics gold medallist biathlete Evi Sachenbacher-Stehle and Italian bobsledder William Frullani.
The Italian Olympic Committee (CONI) announced that Frullani had been sent home from the Games after testing positive for a banned stimulant.
The four-man bobsleigh brakeman underwent testing at the Olympic Village on February 18 where traces of dimethylpentylamine - found in dietary supplements - were discovered.
The German Olympic Sports Confederation (DOSB) announced that Sachenbacher-Stehle had tested positive for the banned stimulant methylhexaneamine.
Meanwhile the IOC confirmed on Saturday that, as a result of Sachenbacher-Stehle's doping case, its disciplinary commission has decided to amend the results of the women's 12.5km mass start and mixed relay events.
Sachenbacher-Stehle, who originally finished fourth in the 12.5km mass start held on Monday, has now been disqualified.
She was also part of Germany's mixed relay team which finished fourth on Wednesday, so the German team has also been disqualified from that event.