The wife of jailed and ailing Kremlin critic Vladimir Kara-Murza said on Monday she was in favour of prisoner exchanges to rescue him and other political prisoners in Russia.

Following the death of Russian opposition politician Alexei Navalny in an Arctic prison colony last month, his team revealed that a deal to free him as part of a prisoner swap had been "at the final stage" before he died.

Asked whether similar discussions were under way for her husband, Evgenia Kara-Murza told reporters in Geneva that she was "not aware of any active negotiations".

"But I know that this was a method of liberating some dissidents in the Soviet times, and I believe that if that was possible in the Soviet times during the Cold War... it is definitely possible today," she said.

Speaking at an event organised by the United Nations correspondents' association ACANU, she acknowledged that due to very limited communication with her husband, she did not know if he would agree to leave if the opportunity presented itself.

"But I believe that in those cases where human lives are at stake, and there is a number of such cases in Russia today... I believe that every method should be used to save these people's lives," she said.

Navalny's death has raised fears for remaining Kremlin critics imprisoned in Russia, of whom Kara-Murza is perhaps the most prominent.

 Punishment cell

 He was sentenced to 25 years in prison last year -- the longest known sentence of all of President Vladimir Putin's jailed critics.

He was charged with "treason" after using a speech in the United States to say Russia had committed "war crimes" against Ukraine.

Kara-Murza, who is also a British citizen, suffers from serious health problems which his wife and lawyers say were due to two poisoning attempts orchestrated by Russia's FSB security service in 2015 and 2017.

Evgenia Kara-Murza said the poisoning attempts had brought on a serious condition called polyneuropathy, which can lead to paralysis.

It figures on the list of medical conditions that should prevent incarceration under Russian law, she said.

"But of course, Vladimir is not only incarcerated," she said.

"He is held in a very strict regime of a punishment cell. For over half a year now, he has not received any medical treatment and obviously his health is deteriorating there."