A Russian court has rejected an appeal by Brittney Griner, a US female professional basketball player who was sentenced to nine years in prison for possessing illegal drugs in Russia.

Griner was detained at an airport near Moscow in February. Authorities say she was carrying cannabis oil in her baggage.

The American appealed the nine-year prison sentence that she received in August, saying the sentence was unjust.

The Moscow Regional Court rejected the appeal on Tuesday.

Griner's lawyers issued a statement, saying that the punishment goes against existing court practices and is excessive. They say they want to consider all possible legal steps.

The US government criticized her detention as unfair. President Joe Biden had a letter delivered to Griner and stressed that he will do his best to secure her release.

The Russian side argues that the sentence is in accordance with the law and not politically motivated.

The conflict between the US and Russia, which is worsening over the situation in Ukraine, is expected to deepen further.