A Russian medallist at this year's Pyeongchang Winter Olympics is suspected of having tested positive for a banned substance, a source at the Games said on Sunday, in a potential major blow to Russia's efforts to emerge from a drug-cheating scandal.
Alexander Krushelnitsky, a bronze-medallist along with his wife in mixed-doubles curling, is suspected of having tested positive for meldonium, the source said.
Meldonium increases blood flow which improves exercise capacity in athletes.
Krushelnitsky did not respond immediately to a request for comment.
A spokesman for the Russian delegation at Pyeongchang said he had no immediate comment.
Russia has been accused of running a state-backed, systematic doping program for years, an allegation Moscow denies.
As a result, its athletes are competing at Pyeongchang as neutral "Olympic Athletes from Russia" (OAR).
Russian sports officials are to meet anti-doping officers at Pyeongchang, the source said, adding any violation would only be confirmed after analysis of a "B" sample.
Krushelnitsky and his wife, Anastasia Bryzgalova, won bronze in a game against Norway, which would take that medal if a doping violation were to be confirmed.
"I hope it's not true ... for the sport of curling," Norwegian team skipper Thomas Ulsrud said.
"If it's true I feel really sad for the Norwegian team who worked really hard and ended up in fourth place and just left for Norway and they aren't even here."
The International Olympic Committee (IOC) said it had taken note of the case without going into details.
It said if the case were to be confirmed, it would be considered by its OAR Implementation panel, the body in charge of monitoring the OAR team's behaviour at the Games.
"On the one hand it is extremely disappointing when prohibited substances might have been used, but on the other hand it shows the effectiveness of the anti-doping system at the Games which protects the rights of all the clean athletes," an IOC spokesperson said.
As neutral athletes, the Russians are unable to have their anthem played in medal ceremonies or use national symbols.
The IOC has said it may allow the Russians to march with the Russian flag and in national uniform at the Games closing ceremony on 25 February, provided they will have complied with its code of conduct on neutrality.
The code requires compliance with IOC anti-doping rules.
