American basketball star Brittney Griner asked US President Joe Biden to free her from a Russian prison in a handwritten letter Monday, portions of which were made public by her family.

Two-time Olympic champion Griner, detained in Russia since February on drug smuggling charges, told Biden she fears she might never be freed.

"As I sit here in a Russian prison, alone with my thoughts and without the protection of my wife, family, friends, Olympic jersey, or any accomplishments, I'm terrified I might be here forever," Griner wrote.

Griner's trial began Friday on charges she tried to smuggle vape cartridges with hashish oil into Russia. She faces up to 10 years in prison. The next hearing in her case is set for Thursday.

US officials have said Griner is being wrongfully detained by Russia, where she has played in the Women's NBA off-season in previous years.

Griner, arrested only days before Russian troops invaded Ukraine, won a 2014 WNBA crown with the Phoenix Mercury. She's a two-time league scoring champion and eight-time All-Star center.

US WNBA basketball superstar Brittney Griner arrives to a hearing at the Khimki Court, outside Moscow on June 27, 2022
US WNBA basketball superstar Brittney Griner arrives to a hearing at the Khimki Court, outside Moscow on June 27, 2022 AFP / Kirill KUDRYAVTSEV

The 31-year-old told Biden in her letter she understands there are many matters he is handling but implored him not to forget her and other Americans being held in Russia.

"I realize you are dealing with so much, but please don't forget about me and the other American Detainees," Griner wrote. "Please do all you can to bring us home.

"I voted for the first time in 2020 and I voted for you. I believe in you. I still have so much good to do with my freedom that you can help restore. I miss my wife! I miss my family! I miss my teammates! It kills me to know they are suffering so much right now. I am grateful for whatever you can do at this moment to get me home."

Griner's letter was presented to the White House on the US Independence Day holiday, which Griner says has an all-new meaning for her this year.

"On the 4th of July, our family normally honors the service of those who fought for our freedom, including my father who is a Vietnam War Veteran," Griner said.

"It hurts thinking about how I usually celebrate this day because freedom means something completely different to me this year."