The UN on Tuesday called on Iranian authorities to immediately release thousands of people who had been detained after participating in peaceful protests, as workers across the country went on strike.
The request came as Tehran stepped up a crackdown against protesters who have carried out two months of nationwide demonstrations, triggered by the death of a young Kurdish woman, Mahsa Amini, in morality police custody.
The spokesman for the office of the UN High Commissioner for Human Rights, Jeremy Laurence, said officials were urging Iran to drop all charges against the demonstrators.
As concerns mount that some of the detained protesters may face capital punishment, Mr Laurence reminded Tehran that it can only hand down the death penalty for the “most serious crimes” under international law.
“Instead of opening space for dialogue on legitimate grievances, the authorities are responding to unprecedented protests with increasing harshness,” Mr Laurence said during a press briefing in Geneva.
At least 10 protesters had been charged with offences that carry the death penalty, including one found guilty of "waging war against God” or “corruption on earth” for damaging public property, Mr Laurence said.
He added that more than 1,000 indictments had been issued against those arrested in connection with protests in Tehran province alone.
"Crimes not resulting directly and intentionally in death can never serve as the basis for the imposition of the death penalty," he said.
"We therefore call on the Iranian authorities to immediately impose a moratorium on the death penalty, to refrain from charging capital crimes and to revoke death sentences issued for crimes not qualifying as the most serious crimes."
Next week, the UN Human Rights Council is expected to hold an urgent session on Iran, with some pushing for an international investigation into the deadly crackdown.
Germany and Iceland have pushed for the formation of a fact-finding team" to look into the reported abuses by authorities against peaceful protesters.
Since mid-September, thousands of Iranians have taken to the streets to protest against the government following the death of Ms Amini, who was arrested after allegedly violating the country's dress code.
The European Union on Monday imposed sanctions on Iran's interior minister and several senior police and military officials over their alleged roles in the security crackdown.
The move comes as various shops in Tehran's Grand Bazaar, the capital's main trade and business hub, were closed on Tuesday following calls for nationwide strikes.
Iran's official news agency called it a "forced strike", claiming "thugs" had forced shopkeepers to close their outlets.
State media routinely labels protesters as "rioters" and "agitators".
In footage shared on social media, commuters in a Tehran metro station were heard chanting "Death to the dictator", a slogan directed at Iran's supreme leader Ayatollah Ali Khamenei.
In Ms Amini's hometown in western Iran, workers put down their tools and university students boycotted classes, said the Oslo-based Hengaw human rights group.
In the province's flashpoint city of Sanandaj, videos shared online showed protesters burning tyres in the street and chanting anti-government slogans.
"Woman, life, freedom" and "Man, homeland, prosperity", chanted young male and females students at Islamic Azad University in the north-western city of Tabriz, in a video published on the 1500tasvir social media channel.