By Nick Butler at the Main Press Centre in Sochi

Vitalijs Pavlovs is one of two further athletes to have tested positive at Sochi 2014February 23 - Latvian ice hockey player Vitalijs Pavlovs and Ukrainian cross-country skier Marina Lisogor have become the third and fourth athletes to fail drugs tests at Sochi 2014.

The positive tests experienced by both were confirmed early Sunday morning by the International Olympic Committee (IOC)) as the organisation officially excluded each from the Games.

Lisogar, as was revealed in a statement posted yesterday on the Ukraine Olympic Committee website, tested positive for the stimulant trimetazidine, which was added to the banned list at the beginning of this year. 

The 30-year-old from Chernihiv in Northern Ukraine competed in the 10 kilometres classical race as well as the qualification of the sprint event at Sochi 2014 and finished in 58th position on each occasion, having previously competing in the Turin 2006 Games.

She claimed to be taking the supplement Preductal to treat a thyroid condition and that she "forgot to declare" the drug on her doping form - but was unaware that is contained a banned substance.

The news is a major blow to Ukraine at such a turbulent time domestically - particularly since the news broke so shortly after the country won a historic and symbolic gold medal in the women's biathlon relay on Friday (February 21). 

The failed test by Pavlovs, meanwhile, emerged only in the IOC statement early this morning,- which explained that he had been disqualified from Latvia's quarter-final against Canada on Wednesday (February 19) and would be excluded from the Games

The statement explained that he tested positive on for methylhexaneamine - thus making him the third athlete of the Games to fail a test for this substance.

This follows the revelations on Friday that German biathlete Evi Sachenbacher-Stehle and Italian bobsleigher William Frullani each failed a test for the stimulant.

It is being reported that the identity of the German is biathlete Evi Sachenbacher but this is yet to be confirmed ©Getty ImagesIt is being reported that the identity of the German is biathlete Evi Sachenbacher but this is yet to be confirmed ©Getty Images

Until Friday no other athletes were known to have failed tests during the Games, although Russian biathlete Irina Starykh was withdrawn from her country's team two weeks beforehand after testing positive.

But, speaking last November, Germany's IOC President Thomas Bach warned countries that a positive drugs test would overshadow the achievement of any team at Sochi 2014.

The anti-doping programme at Sochi 2014 is the  toughest for any Olympics with 57 per cent more tests than at Vancouver 2010.