A hacking group has released footage from one of Iran's most notorious prisons, showing guards beating inmates and dragging an unconscious detainee across the floor.
The violent scenes of abuse reveal the conditions inside Evin prison, which has held political prisoners and many citizens of Western countries, including British-Iranian charity worker Nazanin Zaghari-Ratcliffe.
The videos, which appear to be from the prison's surveillance system, also show guards and prisoners fighting.
The footage also captures the moment prison surveillance system staff realise they've been hacked.
A clip shows prison staff watching a bank of screens flash up with messages announcing the self-described hacker group had taken control of the prison control room monitors.
They flash a message stating "Evin prison is a stain of shame on Raisi's black turban and white beard" and call for "nationwide protests to release political prisoners," according to Sky News.
Reports claimed one scene showed an inmate at the prison smashing a bathroom mirror in an attempt to use the broken glass to self-harm.
The prison has held British-Iranian prisoners on disputed spying charges, including Mrs Zaghari-Ratcliffe, 43, until November last year.
She was released under house arrest and held on charges of undermining the Iranian state, which she disputes.
Authorities in Tehran acknowledged that the videos showing abuses at the Islamic Republic's notorious prison are real, saying he took responsibility for the "unacceptable behaviours".
The head of Iran's prisons issued the rare admission of abuse in an apology on Tuesday, after hackers leaked the footage on social media.
Authorities apologised for the "bitter events" in Tehran's Evin prison, after a hacking group calling itself Edalat-e Ali (Ali's Justice) published the clips online.
"Regarding the pictures from Evin prison, I accept responsibility for such unacceptable behaviour and pledge to try to prevent any repeat of these bitter events and to deal seriously with the wrongdoers," Mohammad Mehdi Hajmohammadi, head of Iran's prisons, wrote in a tweet reported by state media.
"I apologise to God Almighty, our dear leader (Supreme Leader Ayatollah Ali Khamenei), the nation and honourable prison guards, whose efforts will not be ignored due to these mistakes," Hajmohammadi said.
It was a rare admission of human rights abuses in Iran, which often has dismissed criticism of its human rights record as baseless.
Judiciary head Gholamhossein Mohseni Ejei called on Iran's prosecutor-general to "conduct a comprehensive investigation into the situation at Evin prison and the treatment of prisoners by officers ... with speed and accuracy", state TV reported.
Evin prison, which mostly holds detainees facing security charges, has long been criticised by Western rights groups and it was blacklisted by the U.S. government in 2018 for "serious human rights abuses".
"The (Evin) authorities use threats of torture, threats of indefinite imprisonment and torture of family members, deception and humiliation, multiple daily interrogations lasting up to five or six hours, denial of medical care, and denial of family visits," Human Rights Watch said in a report.
In July, Iran also experienced cyberattacks on the website of its transport ministry and the state railway company.
