A hacktivist group that claims to work inside Iran to expose the "true face of the regime" has released new footage highlighting inhumane conditions in the country's most notorious prison.

The new video, provided exclusively to RFE/RL's Radio Farda this week by Edalat-e Ali (Ali's Justice), adds to the evidence of extreme overcrowding at Tehran's Evin prison.

The footage shows prisoners lying wall to wall on floors and stacked three-high on metal bunk beds. As the camera moves from open cell to open cell, each equipped with beds for about 30 inmates, it reveals rooms filled with up to 50 inmates.

RFE/RL could not independently verify the authenticity of the video.

It is unclear when the footage was recorded, but Iran has consistently come under criticism from rights watchdogs for overcrowding and unsanitary conditions at its prisons, a problem that has contributed to COVID infections and deaths.

Edalat-e Ali has released a string of hacked videos and confidential documents that have exposed the systematic mistreatment of inmates at Evin prison. The leaks have even led to rare official acknowledgment that prison abuses were taking place at the facility that primarily houses political detainees.

Previous videos, which were hacked from CCTV cameras and published by Radio Farda among other media outlets, have shown prison guards assaulting detainees and inhumane conditions at the facility. The documents leaked by the hacktivist group have detailed how Evin prison authorities took harsh steps to break hunger strikes by prominent prisoners, including the denial of visitation rights and the blockage of phone access.

Mohammad Mehdi Hajmohammadi, the head of Iran's Prisons Organization, in August issued an apology and accepted responsibility for the "unacceptable behavior" at the prison, while judiciary chief Gholamhossein Mohseni-Ejei ordered an investigation.

It was later announced that members of the prison staff had been suspended and that some cases had been forwarded to a military court. A member of parliament, meanwhile, demanded that those responsible for the publication of the video leaks be punished.

The emergence of the clips also led to harsh criticism from international rights watchdogs.

"This disturbing footage offers a rare glimpse of the cruelty regularly meted out to prisoners in Iran," Heba Morayef, the Middle East and North Africa regional director at Amnesty International, said in August. "It is shocking to see what goes on inside the walls of Evin prison, but sadly the abuse depicted in these leaked video clips is just the tip of the iceberg of Iran's torture epidemic."

The previous month, Amnesty had said that leaked documents that revealed the Iranian government had ignored prison officials' pleas for additional resources to control the spread of the coronavirus were in "stark contrast" to the judiciary's claims that it had introduced initiatives to protect prisoners from the pandemic.

"Overcrowding, poor ventilation, lack of basic sanitation and medical equipment, and deliberate neglect of prisoners' health problems are making Iranian prisons a perfect breeding ground for COVID-19," Amnesty said.

Edalat-e Ali, in an interview with Radio Farda in November, said that it was made up of Iranians working and living in Iran who sought to expose human rights abuses in the country.

In February, the group announced in a call to Radio Farda that the Ghezel Hesar prison in the city of Karaj had been hacked.

The group provided Radio Farda with a list of hundreds of Iranians who were detained during student protests in 1998 and held in Ghezel Hesar prison.