The International Olympic Committee (IOC) has denied applying double standards towards American and Russian athletes amid the Kamila Valieva doping scandal.

Russian teenager Valieva was controversially cleared to go for a second gold of the Beijing Winter Olympics this week despite testing positive for performance-enhancing drug trimetazidine in December.

Valieva won a team figure skating gold last week before her positive test was revealed and is on course to win the singles title on Thursday after leading the way in the short program routine on Tuesday.

The 15-year-old was given the green light to compete at the Capital Indoor Stadium due to "exceptional circumstances", largely due to the her age ensuring she is considered to be a "protected person" under World Anti-Doping Agency (WADA) rules.

American sprinter Sha'Carri Richardson was incensed by that decision, as she was banned from competing in the Tokyo Olympics last year after testing positive for cannabis.

Richardson claimed to have had smoked marijuana after discovering from a reporter that her biological mother had died.

She cited racial discrimination for being unable to go for gold in Japan and questioned how her positive test came to light so quickly compared to Valieva's.

IOC spokesperson Mark Adams on Wednesday stated that the two cases should not be compared.

"You can't talk about double standards in relation to Russian and American athletes, each case is individual," he said.

"Richardson's positive doping test was discovered on June 19, and the result was received before the start of the Olympics. She was suspended for a month. There is nothing in common between these two cases."

Adams confirmed there will be an asterisk placed against the women's figure skating competition in Beijing until Valieva's doping case is concluded and expressed sympathy for the teenager.

"This Games, which has not concluded, concerns an issue in December," he said. "She is in the centre of a lot of speculation. It must be very tough for her.

"We of course are in touch with the team, her welfare is the team's first priority, and obviously we are very careful of that but there's only so much that we can do."