MOSCOW, March 25. /TASS/. Four Sambo wrestlers, including two Russian athletes, tested positive for the banned performance enhancing drug, meldonium, Vasily Shestakov, the president of the International Sambo Federation, told TASS on Friday.

"Sambo did not avoid problems with meldonium abuse as I have received the relevant information," Shestakov said in an interview with TASS. "Doping samples of four wrestlers, including two Russians, tested positive for this substance."

"Our federation stands against any athletic violation and the issue of doping is not an exception," Shestakov said. "We will thoroughly investigate each of the reported cases."

Russian sports was hit early this month by a new case in a chain of doping-related scandals after some of the country’s athletes tested positive for banned substance meldonium.

The drug meldonium (mildronate) was included in the list of preparations banned by the World Anti-Doping Agency from January 1, 2016, after which several Russian athletes tested positive for the banned substance. The presence of the meldonium substance in the athlete’s blood during and between competitions is a violation of anti-doping rules. The substance belongs to S4 class on the WADA blacklist (hormones and metabolic modulators).

WADA spokesman Ben Nichols told TASS earlier this week: "As for meldonium, I can confirm there have been 123 adverse analytical findings (positive samples) since the substance was prohibited on 1st January 2016."

Sambo wrestling originated in Russia in 1920s, when soldiers of the then-Soviet Army developed their own hand-to-hand combat technique. The word Sambo is a Russian acronym, which stands for "self-defense without weapons."