Iranian activist Leila Hosseinzadeh, who was released from prison last week, has accused authorities at the Adelabad prison in the southern city of Shiraz of using drugs on prisoners to control them.
“A horrific crime is being committed against ordinary prisoners,” Hosseinzadeh wrote in a Twitter thread on January 15.
The Iranian activist wrote that, one time after a fight between two prisoners, "a pill was placed into the mouth of one of them, and they were unable to speak properly for a few days."
Hosseinzadeh also wrote that prisoners are being deprived of things such as hot water for bathing, while the cutting of hair is prohibited and reciting the Koran is mandatory.
Iranian prisons have a long history of brutal behavior toward their inmates.
Last year, the hacktivist group Edalat-e Ali, which claims to work inside Iran to expose the "true face of the regime," released video footage highlighting the inhumane conditions in Evin prison, the country's most-notorious prison.
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Leaked Video Exposes Extreme Conditions In Notorious Iranian Prison
Several dual-national Iranians and foreign citizens are being held in Evin prison, mostly on dubious security-related charges.
Among them is Iranian-American Siamak Namazi, who announced in a letter to U.S. President Joe Biden on January 16 that he has launched a seven-day hunger strike to mark his 7 years of detention in Iran.
In the letter, Namazi asked Biden to ensure that all American hostages in Iran are returned to the United States and "in the next seven days, think about their suffering in the prisons of the Islamic republic for just one minute a day."
Namazi was based in Dubai with an oil company when he was detained on espionage charges while visiting family in Tehran in 2015. He was questioned over past associations with U.S. think tanks. The Namazi family says the accusations of espionage are absurd.
Namazi was handed a 10-year prison sentence for "collaborating with the hostile American government." He is now the longest-serving American prisoner in Iran.
Western countries have repeatedly said that Iran is trying to take advantage of foreign countries by taking dual and foreign nationals hostage and then using them in prisoner swaps.
During a current wave of unrest sparked by the death of a young woman while she was detained for allegedly wearing a head scarf improperly, Iranian security forces have taken some 40 foreign nationals into custody, often without revealing any charges.