Two-time Olympic gold medallist Brittney Griner had her appeal against a nine-year prison sentence rejected by a Russian court on Tuesday.

The WNBA star was jailed in August for drug possession and drug smuggling with criminal intent.

Griner was arrested at Moscow's Sheremetyevo International Airport on February 17 for bringing under a gram of cannabis oil into Russia in vape cartridges, with the American stating she had made an "honest mistake."

The eight-time WNBA All-Star was, her lawyers argued, using cannabis for medicinal purposes to treat chronic pain sustained over the course of her career and was not aware cannabis oil was outlawed in Russia.

Exactly a week after her 32nd birthday, Griner on Tuesday took part in the hearing via video link from a penal colony outside Moscow, where she has been imprisoned.

The Phoenix Mercury player once again apologised for an "honest mistake" when she spoke to an appeals court of three judges, saying it had been a "very, very stressful" time for her.

She said: "I really hope that the court will adjust this sentence because it has been very, very stressful and very traumatic. People with more severe crimes have gotten less than what I was given."

Griner was unsuccessful with her appeal, with the judge stating the verdict was upheld "without changes" except for time served in pre-trial detention as part of the sentence.

The United States national security advisor Jake Sullivan responded to the verdict by stating: "We are aware of the news out of Russia that Brittney Griner will continue to be wrongfully detained under intolerable circumstances after having to undergo another sham judicial proceeding today.

"President [Joe] Biden has been very clear that Brittney should be released immediately. In recent weeks, the Biden-Harris Administration has continued to engage with Russia through every available channel and make every effort to bring home Brittney as well as to support and advocate for other Americans detained in Russia, including fellow wrongful detainee Paul Whelan.

"The President has demonstrated that he is willing to go to extraordinary lengths and make tough decisions to bring Americans home, as his Administration has done successfully from countries around the world. The Administration remains in regular touch with representatives of the families, and we continue to admire their courage in the face of these unimaginable circumstances."