Russia has said there are "political overtones" in the decision by the international anti-doping agency WADA to ban use of the drug meldonium, and that it will investigate whether positive tests among its sports stars could have been "provocations".
Russian Deputy Prime Minister Arkady Dvorkovich told Russia's R-Sport agency that law enforcers were already investigating how meldonium had got into the bodies of Russian skaters.
He said each case would be examined to establish whether competitors were to blame or "provocation by unknown persons", according to R-Sport.
Russian sporting figures found to have taken meldonium since a ban came into force on January 1 include figure skater Ekaterina Bobrova, speed skater Pavel Kulizhnikov and short-track speed skaters Semion Elistratov and Ekaterina Konstantinova.
Tennis superstar Maria Sharapova has also tested positive to the banned substance, announcing the positive test came during January's Australian Open.