Updated September 17, 2022 at 2:49 PM ET

President Biden met on Friday with the families of WNBA star Brittney Griner and former Marine Paul Whelan, who are being held in Russia under what the administration has called "intolerable circumstances."

The White House said Biden held separate Oval Office meetings with Griner's wife Cherelle and Whelan's sister Elizabeth. The U.S. continues to negotiate with Russia over a potential prisoner swap to free the two Americans.

"The President held the meetings to reiterate his continued commitment to working through all available avenues to bring Brittney and Paul home safely," White House press secretary Karine Jean-Pierre said in a statement. "He asked after the wellbeing of Elizabeth and Cherelle and their respective families during this painful time."

Biden "appreciated the opportunity to learn more about Brittney and Paul from those who love them most, and acknowledged that every minute they are being held is a minute too long," Jean-Pierre added.

Griner, who's spent the last seven months in Russian custody, was allegedly found in possession of cannabis vape cartridges and sentenced last month to nine years in prison. Whelan was convicted of espionage by a Russian court in 2020 and sentenced to 16 years behind bars.

The president previously spoke with Cherelle Griner in July, shortly after Brittney Griner penned a letter to him, in which she said she was "terrified I might be here forever."

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The Biden administration considers the pair to be wrongfully detained, and a potential prisoner swap has been rumored to include Viktor Bout, a notorious Russian arms dealer who was sentenced to 25 years in 2011.

"As we have said before, we believe that Russia is wrongfully detaining Brittney and Paul under intolerable circumstances," Jean-Pierre said earlier. "And as you know, we have been directly engaged with the Russian government through appropriate channels."

Griner, 31, is a two-time Olympic gold medalist and plays for the Phoenix Mercury. Since 2014, she has also played for Russia's UMMC Ekaterinburg team during the WNBA offseason. She was arrested in February for possessing marijuana vape cartridges as she entered the country to prepare for the playoffs.

Cherelle Griner thanked Biden for the meeting and for his administration's efforts to return Brittney to the U.S.

"I've felt every minute of the grueling seven months without her. I look forward to the day my wife is back home," Griner said in a statement. "Let's share a unified commitment to bringing all Americans home to their families and loved ones."

Whelan, 52, also traveled to Russia openly for years, but was arrested in 2018 and convicted on espionage charges in a secret trial.

Jean-Pierre said she cannot share details about the Biden administration's negotiations with Russia due to security reasons, but did say Russia has not been responsive to their proposal.

"While I would love to say that the purpose of this meeting is to inform the families that the Russians have accepted our offer and we are bringing their loved ones home, that is not what we're seeing in these negotiations at this time," she said.

"The Russians should accept our offer," she added. "They should accept our offer today. We will keep working diligently until the day we get to share that good news."

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