At least 12,000 people were killed in what has been described as the largest killing in Iran's contemporary history, according to a report released by Iran International following extensive verification efforts.

"Based on available data and cross-checking information obtained from reliable sources, including the Supreme National Security Council and the presidential office, the initial estimate by the Islamic Republic's security institutions is that at least 12,000 people were killed in this nationwide killing," the report stipulated.

Other reports put the death toll even higher at some 20,000 killed in four days of country-wide protests.

“Some Iranians who have bypassed the internet shutdown have reported very high volumes of dead protesters on the streets and in hospitals and morgues. Some reports alleged the presence of 700-1,000 dead protesters at just one morgue in Tehran, not accounting for other locations around the capital or the country overall,” Institute for the Study of War (ISW) said in its Iran update on January 13. “Other Iranians have claimed that the regime’s crackdown is much greater than the one it conducted in November 2019, during which security forces killed around 1,500 protesters. This anecdotal information is mostly consistent with the regime killing many thousands in its crackdown.”

Due to an internet blackout reports are almost impossible to verify but there is little doubt that killings are widespread and extensive. Videos posted to social media show morgues with body bags piled up on the floors as relatives go to collect the bodies of their loved ones. Others show a reported million people on the street in Tehran and of security forces in trucks with a 50mm heavy machine gun mounted on the back.

Iran International reported that Iranian security forces were conducting house-to-house searches to confiscate satellite dishes and Starlink internet equipment, thereby extending the Islamic regime’s internet crackdown.

Iran International's editorial team conducted a multi-stage verification process, reviewing information from sources close to the Supreme National Security Council, presidential office contacts, Islamic Revolutionary Guard Corps personnel in Mashhad, Kermanshah, and Isfahan, along with testimonies from eyewitnesses, families of victims, medical centre data, and healthcare workers.

"In the largest killing in Iran's contemporary history – carried out largely over two consecutive nights, Thursday and Friday, January 8 and 9 – at least 12,000 people were killed," the report concluded, noting that victims were primarily shot by Revolutionary Guard Corps and Basij forces.

CBS News corroborated these figures. "Activist groups working to compile a full death toll from the protests, based on reports from medical officials across the country, believed the toll was at least 12,000, and possibly as high as 20,000," a source inside Iran told the US news agency.

Iranian officials have not provided regular casualty estimates. Reuters quoted an unnamed Iranian official claiming approximately 2,000 deaths since protests began on December 28, attributing the violence to foreign-influenced "terrorists."

The crack down and killings may be starting to have an effect, at least in the largest cities. ISW recorded seven protests across six provinces on January 13, compared to 156 protests across 27 provinces on January 8.

But ISW continued to record protests primarily in large cities, such as Tehran where an estimated one million people took to the streets, as well as Esfahan and Tabriz.

“The Iranian regime has historically struggled to suppress unrest in less populated and rural areas more than in urban areas. It would therefore be surprising if protests continued to take place in large cities and not in smaller towns and villages,” ISW said.