US President Joe Biden has announced that US professional basketball player Brittney Griner has been freed from prison in Russia, and is now safe in American custody.

Biden said Griner was on a plane on her way home. He made the announcement alongside Griner's wife, Cherelle.

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

The 32-year old American was sentenced to nine years in prison in August for alleged drug possession.

Griner was freed in an exchange for convicted Russian arms dealer Viktor Bout, who was held in the US.

Bout was known as "The Merchant of Death." He had been sentenced to 25 years in prison in 2012 for conspiring to sell arms that would be used against Americans.