Rights campaigners are urging the Russian government to consider releasing some pre-trial detainees and prisoners held in the country's packed jails, warning of the "devastating consequences" of the coronavirus pandemic.
More than half a million people are held in Russia's notoriously crowded prisons in what is the European continent's largest prison population.
In a letter Tuesday to Russian government agencies, UK-based rights group Amnesty International said that "urgent measures are needed" to deal with the COVID-19 outbreak.
"Overcrowding, poor ventilation and inadequate healthcare and sanitation" expose Russian prisoners to a higher risk of infection, said Amnesty.
It warned of "devastating consequences" if the country does not protect its vulnerable prison population.
Amnesty said that at least 9,000 people out of Russia's prison population are over 60, while 97,000 are detainees still awaiting trial.
Russia "should urgently consider releases" of some pre-trial detainees and prisoners, it said.
Rights activists with the Moscow Helsinki Group late last week launched a petition calling for a major prisoner amnesty to avoid "an almost inevitable COVID-19 epidemic in prisons and detention facilities".
More than 4,500 people have signed the petition so far.
Last week Human Rights Watch also criticized Russia's response to the pandemic.
It "has involved ending family visits without increasing inmates' access to more phone calls, and general commitments to protecting inmates' health without making specific plans public," it said.
Some countries including Iran and Afghanistan have moved to release thousands of prisoners to lower the risk of a major outbreak of the virus in prisons.
The coronavirus has caused increased violence and riots, as facilities around the world introduced quarantines.
The UN rights chief Michelle Bachelet last week said countries should consider releasing older detainees and low-risk offenders.