The UN Human Rights Council will hold an emergency session on Friday to discuss the "alarming violence" used in Iran against protesters, while a group of states will call on United Nations' investigators to document alleged abuses for future trials.
Rights groups say thousands, including bystanders, were killed during the unrest, which represented the biggest challenge to Iran's clerical government since 2022.
At least 50 countries backed the call for a special session of the UN Human Rights Council to address credible reports of violence, crackdowns on protesters and violations of international human rights law across the country, according to a letter drafted by Iceland.
"The scale of the crimes is unprecedented," Payam Akhavan, a former UN prosecutor with Iranian-Canadian nationality, told Reuters ahead of the session, where he is set to speak.
"We are trying to set the stage for transitional justice in Iran, for the country’s Nuremberg moment, should that come to pass," he said, referring to the international criminal trials of Nazi leaders following World War Two.
Iran's diplomatic mission did not immediately respond to a request for comment. Authorities have blamed the unrest and deaths on "terrorists and rioters" backed by exiled opponents and foreign adversaries, the United States and Israel.
Proposal seeks to extend UN mandate
The proposal before the Geneva body seeks to extend by two years the mandate of a UN investigation set up in 2022 after the previous wave of protests. It would also launch an urgent investigation into violations and crimes linked to the latest unrest that began on December 28 "for potential future legal proceedings."
It was not clear who would cover the costs amid a UN funding crisis that has stalled other probes.
Human rights advocates hope that the emergency session will pressure Iran's government.
"The session sends a strong message to Iranian authorities that the international community is closely monitoring their actions and will not tolerate the suppression of dissenting voices," said Azadeh Pourzand, the spokesperson for Impact Iran, which is a coalition of 19 non-governmental organizations campaigning for human rights in Iran.