Five-time world champion Pavel Kulizhnikov is one of three Russian speedskaters who tested positive for the banned drug meldonium and were provisionally suspended, the International Skating Union has said.
Kulizhnikov faces a possible lifetime ban for a second offense. He previously was suspended in 2012 for using the banned substance methylhexanamine.
The two other Russian speedskaters, Olympic relay gold medalist Semyon Elistratov and short-track racer Yekaterina Konstantinova, face potential four-year bans since for them it is a first offense.
Russian Skating Union President Aleksei Kravtsov told the R-Sport news agency on March 18 that the positive drug tests "do not change anything for us."
"We are still confident that our athletes are not guilty and we will defend them."
Meldonium was added to the World Anti-Doping Agency's list of banned substances on January 1.
While 102 athletes have tested positive for meldonium worldwide since January 1, most of the 14 known cases so far have involved Russian athletes.
The International Olympic Committee on March 18 applauded what it called a "strong statement" by Russian President Vladimir Putin earlier in the week directing Russian sports officials to speed up efforts to root out the drug problem and refrain from "promoting conspiracy theories" to deflect responsibility.
"This is a strong statement that demonstrates a clear commitment by the Russian authorities to tackle this problem," the committee, based in Lausanne, Switzerland, said.
Russia hopes to clear its record on drugs in time for its track and field team, which was suspended for doping last year, to participate in the 2016 Summer Olympics in Rio de Janiero in August.
