There is controversy over the magnitude of the novel coronavirus outbreak in Iran, which according to official figures has left almost 5,300 people dead.
The uncertainty is even greater over the effects of COVID-19 within Iran's overcrowded prisons, estimated to hold a quarter of a million people.
This comes as activists and supporters of political prisoners are sounding the alarm over the risk that the disease has already penetrated deep into the Iranian prison system, even as officials insist the outbreak is beginning to slow.
The anxiety over the virus became so acute in some prisons that, according to Amnesty International, inmates rioted in at least eight sites across Iran, sparking a crackdown by the security forces that left 36 prisoners dead.
The prison riots were "among the most significant of the last years and show the great concerns of those detained," Katia Roux of Amnesty International France told AFP, expressing concern about the fate of hundreds of others who were wounded in the unrest.
She complained of "pitiful sanitary and hygiene conditions" in Iranian jails, which lacked ventilation and access to water sources.
"The authorities do not allow access to appropriate care: no tests and no quarantine of people who get sick," she added.
For its part, Iran claims it has released around 100,000 inmates, including 1,000 foreigners, to ease the pressure on the prison system during the outbreak. However, dual nationals and prominent detainees regarded by the international community as prisoners of conscience have been kept behind bars, despite the risk of infection.
Some well-known foreign detainees have been allowed to go free. Roland Marchal, a French researcher arrested in June 2019, returned to France last month. Nazanin Zaghari-Ratcliffe, a dual British-Iranian citizen, was allowed leave on a temporary furlough.
But most prisoners of conscience and dual and foreign nationals remain imprisoned, United Nations special rapporteurs warned in a statement last week, AFP reported.
"Some are at great risk from COVID-19 due to their age or underlying health conditions," the statement said.
The list of dual national and political detainees who remain in Iranian jails is grimly long, including Fariba Adelkhah, another academic with French-Iranian nationality who was detained at the same time as Marchal.
Another hearing in her trial on national security charges took place on Sunday.
"The fears are real, given the seriousness of the health situation in the country; Fariba is in a cell with several other people," said Jean-Francois Bayart, a professor at the Graduate Institute of International and Development Studies (IHEID) in Geneva and a member of Adelkhah's support committee.
He noted that the number of female prisoners had recently decreased, and that masks and sanitary gels were available.
Meanwhile, Tehran denies holding political prisoners and insists that everything has been done to ensure the well-being of inmates during the virus outbreak.
The impact of the virus in Iran remains a matter of debate -- according to official figures over 5,000 people have died.
