The analysis of B-samples for four leading Russian skaters have all tested positive for meldonium, the International Skating Union (ISU) have confirmed.
It leaves all four facing the prospect of bans which could rule them out of the 2018 Winter Olympics in Pyeongchang.
Long-track star Pavel Kulizhnikov pulled-out of the ISU World Cup Final in Heerenveen earlier this month after his failure was first reported.
The 21-year-old successfully defended his world sprint title earlier this season and claimed two gold medals at the World Single Distances Championships last month in Kolomna in Russia.
He still claimed the overall 500m World Cup crown, despite missing the season finale, although he could now be retrospectively disqualified if he is given a suspension as a result of his positive drugs test.
Kulizhnikov, winner of five World Championshps titles in total, previously served a two-year doping ban between 2012 and 2014
He had positive for the stimulant methylhexanamine at the 2012 World Junior Championships in Obihiro in Japan, where he won gold medals in the 1,000m event as a 17-year-old.
He thus faces a long suspension for a second offence, possibly even a life ban.
Two leading short-track stars have also failed, including Semen Elistratov. the 2015 world champion in the men’s 1,500 metres
The 25-year-old Olympic relay champion earned the 1,000m, 1500m and overall titles at the European Championships in January, an event held in Sochi.
He missed the World Championships in Seoul last weekend after testing positive, although he initially blamed illness for his absence.
Ekaterina Konstantinova, a gold medallist in the women’s relay at the 2015 European Short Track Speed Skating Championships in Dordrecht in The Netherlands has also failed both A and B samples.
They are joined by ice dancer Ekaterina Bobrova, an Olympic gold medallist at Sochi 2014 as part of the Russian squad which won the team competition.
She tested positive at January's European Figure Skating Championships in Bratislava, where, together with partner Dmitri Soloviev, she won a bronze medal.
Numerous Russians in several sports have either failed or reportedly failed for meldonium since the substance was added to the World Anti-Doping Agency (WADA) banned list on January 1.
These include tennis superstar Maria Sharapova, who has admitted to failing during the Australian Open in January, and four-time world swimming champion Yuliya Efimova, who also failed a drugs test for the second time in her career.
Russian rugby and volleyball players have also failed, as well as biathletes, cyclists and bobsledders, with many more cases expected.
Russia is not the only country to have had problems.
Other high-profile cases have involved Ethiopia's Tokyo Marathon winner Endeshaw Negesse, Sweden's Ethiopian-born former world 1500 metres champion Abeba Aregawi and Ukrainian runner Nataliya Lupu, the European Indoor 800m champion in 2013.
Developed in Lativa, meldonium was moved from the monitored to the prohibited list by WADA due to “evidence of its use by athletes with the intention of enhancing performance”.
Although also prescribed as a prescription drug, meldonium was reportedly used by Soviet troops fighting in the Afghanistan War to boost their endurance.