The Siberian Indoor Championships saw an exodus of Russian athletes last weekend when more than 30 withdrew from the competition after drug testing officials entered the scene.
According to the Russian sports website Championat, as many as 36 athletes cited various illnesses for withdrawing from the competition at the city of Irkutsk.
The Russian track and field federation "has started an internal investigation" into the incident, according to Championat.
The incident follows a ban issued last month prohibiting Russian athletes from competing under their own flag at the upcoming Winter Olympics after allegations of doping during the 2014 Olympic Games in Sochi.
"[We] have a lot of problems at the bottom [of athletics in Russia]," [Russian Athletics Federation President Dmitry Shlyakhtin] said.
"Our suspicion that the doping situation hasn't improved in all regions has increased," he said, adding that without documentation, he could not be sure that the athletes who withdrew were using illegal drugs.