US Basketball star Brittney Griner, who was in a prison in Moscow, has been swapped for arms dealer Viktor Bout ©Getty Images

Tokyo 2020 basketball champion Brittney Griner, who was in a prison in Moscow on drugs charges, has been swapped for arms dealer Viktor Bout.

United States President Joe Biden negotiated the release of Griner, who was arrested for possessing cannabis oil shortly prior to the Russian invasion of Ukraine and was sentenced to nine years in prison.

Biden posted on his Twitter page that Griner is safe and on her way home, ending a long saga that began in February this year.

"As a result of the efforts made, it was possible to agree with the American side on organising the exchange of Viktor Bout for Brittney Griner," the Russian Foreign Ministry was quoted as saying by state news agency TASS.

"The Russian citizen was returned to his homeland.

"Washington categorically refused to have a dialogue on including a Russian in the exchange scheme.

"Nevertheless, the Russian Federation continued to actively work to rescue our compatriot."

Bout, nicknamed the "Merchant of Death", was serving a 25-year jail term, convicted on four counts of conspiracy to kill Americans, acquire and export anti-aircraft missiles and providing material support to a terrorist organisation.

Bout, whose life inspired the 2005 Hollywood film Lord of War, was arrested in Bangkok in 2008 and was sentenced to 25 years in federal prison in 2012. 

The swap took place in Abu Dhabi and there is no change in the status of  Paul Whelan, who was involved in the initial swap discussions between the two nations. 

Whelan is a US citizen imprisoned in Russia on espionage convictions.

According to NBC, Griner's wife, Cherelle Griner, spoke to her on the phone from the Oval Office with Biden.

A senior White House official said that Griner will be flown to a medical facility in San Antonio for care.

Griner starred for the US at the Olympics, helping the women's basketball team to win back-to-back gold medals at Rio 2016 and Tokyo 2020.

The 31-year-old has been playing in Russia since 2014 and was flying to play for UMMC Ekaterinburg of the Russian Premier League at the time of the arrest.

Viktor Bout was arrested in Bangkok in 2008 and was sentenced to 25 years in federal prison in 2012 ©Getty Images
Viktor Bout was arrested in Bangkok in 2008 and was sentenced to 25 years in federal prison in 2012 ©Getty Images

"She [Griner] will soon be back in the arms of her loved ones and she should have been there all along," Biden was quoted as saying by NBC.

"I'm proud that today we have made one more family whole.

"We’ll keep negotiating for Paul’s relief. 

"I guarantee it."

Cherelle Griner expressed her "sincere gratitude" to Biden other officials for helping to get her partner back to the United States.

Griner and her legal team have always maintained that the crime was not committed on purpose and that the cannabis oil, which was prescribed to treat chronic pain, was only in her luggage as she had packed in a hurry.

The Biden administration had faced domestic pressure to secure Griner's release, but US sanctions levied against Russia in response to the war in Ukraine complicated diplomatic efforts.

In April, former American marine Trevor Reed was released after spending nearly three years in a Russian jail, making it the second known prisoner swap since the war in Ukraine started.  

Reed was freed in exchange for Konstantin Yaroshenko, a convicted Russian drug trafficker, who was serving a 20-year sentence in a US prison in Connecticut since 2010.