The families of US basketball star Brittney Griner and former Marine Paul Whelan have asked veteran hostage negotiator Bill Richardson to seek their release from Russia, his office said Monday.

According to news reports, the former US governor and ambassador -- who has negotiated the freedom of several Americans held prisoner by other countries -- will travel to Russia in the coming weeks for talks.

Mickey Bergman, vice president of the Richardson Center for Global Engagement, would not confirm the reports. 

"What I can say is that both the Whelan and Griner families have asked us to help with the release of their loved ones," he told AFP.

Richardson has had a record since the 1990s of negotiating the release of US citizens imprisoned in countries such as North Korea and Myanmar.

While he acts as a private citizen, his involvement usually has the tacit blessing of the US government.

He held discussions with Russian officials over the past two years for the release of another American, former US Marine Trevor Reed.

Reed was freed in April when the two governments agreed to swap him for Russian pilot Konstantin Yaroshenko, who was jailed in the United States for drug trafficking.

Asked about Richardson's role, White House national Security Advisor Jake Sullivan said the administration had been in contact with him.

"President Biden is laser-focused on a government-to-government solution to this issue," Sullivan told reporters.

"We are working directly with the Russian government through appropriate channels to try to bring a speedy resolution not just to her case, but to Paul Whelan's case as well."

Held in Russia

Griner, a two-time Olympic basketball gold medalist and WNBA champion who had played in Russia, was detained in February, just one week before Moscow launched its invasion of Ukraine.

The 31-year-old was charged with drug smuggling for possessing vape cartridges with cannabis oil.

On July 7, she pleaded guilty and now faces up to 10 years in a Russian prison.

Whelan, a security official at an auto parts company and a former US Marine, was arrested in Moscow in December 2018 for allegedly holding classified materials.

He was convicted of espionage in June 2020 and sentenced to 16 years in prison. 

Griner's case has been enmeshed in the freeze in US-Russia relations since the invasion of Ukraine.

President Joe Biden was accused of ignoring her plight until he spoke on the phone last week with Griner's wife. 

Shortly after that, Biden also spoke with members of Whelan's family.

David Whelan, Paul's brother, underscored that Richardson does not have a mandate from the Biden administration for negotiations.

"The hope is that Governor Richardson may be able to have discussions that are not possible when you are limited to governmental channels," he told AFP.

After Griner's conviction, former US ambassador to Russia Michael McFaul urged the Biden administration to exchange imprisoned Russian arms deal Viktor Bout for the two Americans.

"Tragically, the only leverage we have is a Russian in detention," McFaul said Thursday on NBC News.

"Viktor Bout is a real criminal... and the Russians want him out," said McFaul.

A swap "might be the only way to get Brittney Griner out as soon as possible," he said.