UN High Commissioner for Human Rights Zeid Ra'ad al-Hussein has described the hanging of up to 20 people in Iran this week as "a grave injustice."
In an August 5 statement, Hussein said the executions followed "the application of overly broad and vague criminal charges, coupled with a disdain for the rights of the accused to due process and a fair trial."
Reports suggested most -- if not all -- those executed this week were Sunni Muslims from the Kurdish community.
Official said the men came from Kurdish areas and belonged to the extremist Tawhid and Jihad group.
Iran, which is predominantly Shi'ite, executed at least 977 people last year, according to Amnesty International.
The organization said Iran was the second-most-prolific executioner in the world last year, after China.