The Biden administration has made a “substantial offer” to bring two American detainees home from Russia, the US Secretary of State has said.
Reports have suggested Moscow is interested in trading basketball star Brittney Griner for convicted Russian arms trafficker Viktor Bout.
Secretary Antony Blinken said he would raise the matter in a call next week with Russia’s foreign minister.
Mr Blinken and Sergei Lavrov have not spoken since the war in Ukraine began.
Speaking to reporters at the State Department, Mr Blinken said he could not disclose details of the proposed swap.
According to CNN, the US hopes to trade Bout for Ms Griner and fellow American detainee Paul Whelan.
“We made a substantial proposal weeks ago and the US government continues to work aggressively, pursuing every avenue, to bring Brittney Griner and Paul Whelan home,” a White House official told CBS News, the BBC’s partner in the US.
Such a deal would be the first concrete action announced by the US government with regard to the release of Ms Griner.
The 31-year-old has been in custody since February after Moscow airport officials allegedly found cannabis oil in her luggage, while she was returning to the US after playing in Russia.
At her drug possession trial on Wednesday, Ms Griner said the officials made her sign documents but “no one explained any of it to me”.
She also claimed she received neither an explanation of her rights nor access to a lawyer in the initial hours of her detention, forcing her to use a translation app on her phone to communicate.
The two-time Olympic gold medallist has pleaded guilty to the drug charges against her, but denied deliberately breaking the law, saying she had packed her bags in a rush.
“I still don’t understand to this day how [the vape cartridges] ended up in my bags,” Ms Griner said.
“With them being accidentally in my bags, I take responsibility, but I did not intend to smuggle or plan to smuggle anything into Russia.”