Iran has turned its prisons into sites of mass killing with at least 853 people executed in the Islamic republic in 2023, over half of them on drug-related charges, Amnesty International said on Thursday.
The London-based group said in a report that stronger international action was needed to halt the rise in executions, otherwise "thousands" risked being hanged in the coming years.
The Iranian authorities have "persisted with their state-sanctioned killing spree which has turned prisons into killing fields", Amnesty said.
The figure for 2023 was up 48 percent on the previous year and 56 percent of executions involved drug-related charges, Amnesty said.
Two other NGOs, Iran Human Rights (IHR) and Together Against the Death Penalty (ECPM), published a report last month giving the slightly lower figure of 834 people executed in 2023.
The surge in executions came after Iran was convulsed by protests that erupted in September 2022. Nine people have been put to death in cases related to the protests.
Rights groups including Amnesty have warned that the authorities are using executions to instill fear throughout society and prevent any more demonstrations.
Amnesty said Iran's behaviour had not changed this year, with at least 95 executions already recorded up to March 20.
The rights group added that its numbers were "minimum figures" and the real death toll would be higher.
"Without a robust global response, Amnesty International fears that the Iranian authorities will continue using the death penalty as a tool of oppression to execute thousands more people in the coming years," the group said in its report.
Among those executed was 17-year-old Hamidreza Azari, hanged in November in Razavi Khorasan province after being convicted over a deadly 2023 stabbing when he was 16.
His age "was misrepresented" as 18 by state media to "evade accountability", Amnesty said, adding that it had reviewed his birth certificate.
Amnesty said the Sunni Baluch minority concentrated in the southeast was being targeted disproportionately.
The minority "constitutes only about 5 percent of Iran's population but accounted for 20 percent of all executions in 2023", the report noted.
And the renewed surge in executions for drug offences was a particular concern, Amnesty said.
Iran's anti-narcotics legislation was modified in 2017 and executions for drug offences declined in 2018 and 2020 before dramatically rebounding last year.
"The death penalty is abhorrent in all circumstances but deploying it on a mass scale for drug-related offences after grossly unfair trials before Revolutionary Courts is a grotesque abuse of power," said Diana Eltahawy, Amnesty's deputy regional director for the Middle East and North Africa.