The two-time Olympic gold medallist was arrested on February 17th at a Moscow airport with vape cartridges containing cannabis oil in her luggage, and was sentenced on August 4th to nine years in a penal colony on drug smuggling charges. Her appeal is due to be heard next Tuesday.

"All the support and love are definitely helping me," Griner was quoted as saying by her lawyers Maria Blagovolina and Alexander Boykov, who spent several hours with her in the Moscow pre-trial detention centre where she is being held.

Griner pleaded guilty at her trial but said she had made an "honest mistake" and not meant to break the law. Cannabis is illegal in Russia for both medicinal and recreational purposes.

"Today is of course a difficult day for Brittney," said Blagovolina, who is representing Griner in court.

"Not only is this her birthday in jail away from her family, teammates and friends, but she is very stressed in anticipation of the appeal hearing on October 25th."

Washington says Griner was wrongfully detained and has offered to exchange her for Viktor Bout, a Russian arms dealer serving a 25-year prison sentence in the United States. It said last week it had had no consular access to her since August.

Moscow has also suggested it is open to a prisoner swap.

Bill Richardson, a former US ambassador to the United Nations who travelled to Moscow in September, has said he believes Griner and former US Marine Paul Whelan could both be released by the end of the year.