Secretary of State Antony Blinken described jailed U.S. basketball player Brittney Griner's transfer from a Russian jail to a penal colony as "another injustice."

"Following a sham trial and the unjust sentencing of Brittney Griner, Moscow is transferring her from a prison in Moscow to a remote penal colony," Blinken said in a statement Wednesday. "It is another injustice layered on her ongoing unjust and wrongful detention."

According to a report by Poland-based think tank the Centre for Eastern Studies, most of Russia's prisons are actually penal colonies, where inmates are housed in cramped barracks and are frequently put to work.

As of 2019, more than 800 penal colonies existed throughout Russia, the organization said.

Dating largely from the Soviet era, the facilities have been compared to Joseph Stalin's gulags – harsh prison camps that were in use in the mid-20th century.

Griner was detained in Russia earlier this year after authorities claimed they found vape canisters of cannabis oil in the two-time Olympic gold medalist's luggage at a Moscow airport. In August, she was convicted of drug possession and sentenced to serve nine years in a Russian penal colony.

The WNBA All-Star's appeal of her sentencing failed last month and her attorneys said Wednesday that she had been moved to the penal colony.

"Brittney was transferred from the detention center in Iksha on the 4th November," her legal team said in a statement, according to The Hill. "She is now on her way to a penal colony. We do not have any information on her exact current location or her final destination."

The State Department "will not relent" until Griner and Paul Whelan, another American being held by Russia, are returned to the United States, Blinken said Wednesday. He also called for transparency from Russia on the prisoners' health and welfare.

Whelan, a U.S. Marine veteran, was arrested for espionage in 2018 and is serving 16 years in prison.

The U.S. has reportedly been exploring the possibility of a prisoner swap with Russia to free Griner and Whelan.

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