The UN's Office for the High Commissioner for Human Rights (OHCHR) has expressed "deep concern" about the increase in executions in Iran this year.
The OHCHR said at least 80 people had been killed by Iran in about seven weeks.
It said the majority were for drug-related crimes.
The OHCHR said drug offenses did not, under international law, constitute "most serious crimes" generally used to apply capital punishment.
The UN body said it was most concerned by the executions of Hadi Rashedi and Hashem Shabani Amouri.
Members of Iran's Ahwaz Arab community, Rashedi and Amouri were executed in January after being found guilty of "enmity against God," "corruption on Earth," and acting against Iran's national security.
They were reportedly tortured in detention and given unfair trials.
Iran is reported to have executed at least 500 people in 2013.