Top Russian biathletes Irina Starykh and Ekaterina Iourieva have tested positive for the banned substance EPO, the International Biathlon Union and Russian officials confirmed Saturday.
Irina Starykh practises during the warm up shooting of the women's 15 km individual event at the Biathlon World Cup on January 10, 2014, in Ruhpolding, southern Germany
Starykh and Iourieva gave their samples on December 23 at the World Cup event in Pokljuka, Slovenia and both 'A' and 'B' samples tested positive for the blood booster Erythropoietin (EPO), the IBU said.
Earlier this year, Starykh was provisionally suspended and excluded from the country's Olympic squad at her request after the IBU had announced that three biathletes representing Russia and Lithuania had failed dope tests.
That news cast a shadow over Russia's preparations for the February Winter Olympics in Sochi even though Starykh, a potential medal contender, had withdrawn herself from the team.
Iourieva, 30, who has already served a two-year ban for doping, announced her intention to retire on February 27.
But Russia's Sports Minister Vitaly Mutko announced that the ministry was set to issue an appeal over the Starykh case in a civil court, saying the objective character of the assessment of her samples was in question.
"We have some witnesses in the favour of Starykh," Mutko said. "Our lawyers are preparing to struggle for the rights of our biathletes."
Russia has sought to clean up its act on doping but the positive tests for two high profile biathletes will be seen as one of the biggest doping scandals in Russia in recent times.
Ahead of the 2010 Vancouver Olympics, three of Russia's best known biathletes –- Dmitry Yaroshenko, Albina Akhatova and Iourieva herself –- were disqualified for using EPO.