Iran's judiciary chief has blamed "enemy agents" for clashes and fire at Tehran's high-security Evin Prison, calling on security agencies to identify the main perpetrators.
Mohsen Ejei made the remarks on Monday during his weekly meeting with senior judiciary officials, two days after the incident that has left at least eight prisoners dead.
The death toll rose on Monday after four more prisoners died at a hospital, the judiciary's media center said.
On Sunday, it said four inmates had died due to "inhalation of smoke" as a result of the fire, while 61 others were injured, some of them critically.
The incident took place on Saturday, with initial media reports suggesting clashes between inmates and the prison staff.
On Sunday, Mizan News Agency, affiliated with the country's judiciary, said clashes had broken out between two groups of prisoners at a sewing workshop inside the prison. According to media reports, some prisoners set the warehouse of clothes and the sewing workshop on fire.
Ejei blamed a "few enemy agents" for setting fire to a workshop that he said was established to "provide employment to prisoners and help their families".
The top judiciary official called on the prisons organization to identify the main perpetrators of the incident, with the help of security agencies, and introduce them to prosecution.
Evin Prison in north Tehran's upscale Saadabad neighborhood is the biggest detention center in the country that holds thousands of prisoners, including dual nationals arrested for alleged spying.
In a statement on Sunday, the US Department of State said it was “following reports" from the prison with "urgency”.
“We are in contact with the Swiss as our protecting power. Iran is fully responsible for the safety of our wrongfully detained citizens, who should be released immediately,” the statement said.
European Union foreign policy chief Josep Borrell also tweeted on Sunday, saying he was following reports on the situation in Evin Prison.
"Iranian authorities are responsible for lives of all detainees, including human rights defenders and EU nationals. Expressed my most serious concern to FM [Hossein] Amir-Abdollahian. We expect maximum transparency on the situation," he wrote.
In response, Iranian Foreign Ministry spokesman Nasser Kanaani at a weekly presser on Monday condemned what he termed "baseless stances, hasty and interventionist behavior" of Western officials on the incident.