Originally Published: 27 JUN 22 06:22 ET

Updated: 27 JUN 22 12:43 ET

By Anna Chernova and Dakin Andone, CNN

(CNN) -- A Russian court on Monday scheduled Brittney Griner's trial to start Friday, according to her lawyer, and ruled the WNBA star's detention be extended six months pending its outcome.

Griner -- who has been held in Russia since her arrest at a Moscow airport on allegations of attempted drug smuggling -- attended the preliminary hearing in person Monday, arriving at court handcuffed and flanked by guards in black vests, according to a photo by AFP photographer Kirill Kudryavstev. She wore a gray T-shirt and glasses, the photo shows.

Boykov previously told CNN the hearing would occur behind closed doors at the Khimki court, just outside Moscow.

Griner, 31, a Phoenix Mercury player who plays in Russia during the WNBA's offseason, was arrested February 17. Russian authorities claimed she had cannabis oil in her luggage and accused her of smuggling significant amounts of a narcotic substance, an offense punishable by up to 10 years in prison.

The US State Department, however, has classified Griner as "wrongfully detained," a department official told CNN in May.

Griner's detention, which has been repeatedly extended, has sparked a wave of support among dozens of organizations in the US that have joined Cherelle Griner, Brittney Griner's wife, in urging President Joe Biden to strike an exchange deal with Russian authorities to release Griner and bring her home safely as soon as possible.

Griner's supporters have expressed concern that she might be used as a political pawn, given rising tensions amid Russia's invasion of Ukraine.

READ: Dozens of organizations sign letter calling on President Biden to strike deal for Brittney Griner's release

More than 40 organizations -- including the National Association for the Advancement of Colored People, Human Rights Campaign, GLAAD, the National Urban League and the Women's National Basketball Players Association -- signed a letter addressed to President Biden and Vice President Kamala Harris.

US Secretary of State Antony Blinken spoke to Cherelle Griner one-on-one last Wednesday, according to a senior State Department official. She said last week she hasn't talked to her wife since February 17.

"I've got no higher priority than making sure that Americans who are being illegally detained in one way or another around the world come home," Sec. Blinken told CNN's "State of the Union" at the Group of 7 summit Sunday.

"That includes Paul Whelan, that includes Brittney Griner, that includes people in a number of other countries," he added. Whelan is a US citizen who was detained in Moscow in 2018 and arrested on espionage charges. He has denied the charges.

"I can't comment in any detail on what we're doing, except to say this is an absolute priority," Blinken said.

Griner was named an honorary WNBA All-Star Game starter last week, with the All-Star Game scheduled to take place on July 10 in Chicago.