Hopes are growing in Russia for a possible prisoner swap with the United States.
The former Soviet officer Viktor Bout (Russian: But), who was imprisoned in the United States for arms trafficking, was also discussed.
According to the Interfax news agency, Deputy Foreign Minister Sergei Ryabkov said in Moscow on Friday.
"We haven't come to a common denominator yet, but there is no dispute that Bout is one of those people who are being talked about," said the senior Russian diplomat.
"And of course we hope for a positive result."
Despite the strained relationship between Washington and Moscow, there have been contacts for months about an exchange of prisoners.
According to American media reports, this was also an issue when the head of the CIA, William Burns, and his Russian counterpart, Sergey Naryshkin, met in Istanbul in mid-November.
Above all, the United States wants to free basketball player Brittney Griner, who has been convicted of a drug offense in Russia.
According to information on Thursday, she was transferred to a penal camp in the Mordovia region on the Volga.
It is also about the American Paul Wheelan, who is in prison for alleged espionage in Russia.
Bout, known as the "Dealer of Death", is said to have illegally equipped regimes and rebels in numerous countries with weapons.
He has been imprisoned in the United States since 2010.