Amnesty International and Human Rights Watch said Ebrahim Raisi's election as Iran's new president was a blow for human rights and called for him to be investigated over his role in what Washington and rights groups have called the extrajudicial executions of thousands of political prisoners in 1988.
Iran has never acknowledged the mass executions and Raisi has never publicly addressed allegations about his role. Some clerics have said the trials were fair, praising the "eliminating" of armed opposition in the early years of the 1979 Islamic revolution.
"That Ebrahim Raisi has risen to the presidency instead of being investigated for the crimes against humanity of murder, enforced disappearance and torture, is a grim reminder that impunity reigns supreme in Iran," London-based Amnesty Secretary General Agnès Callamard said in a statement.
"We continue to call for Ebrahim Raisi to be investigated for his involvement in past and ongoing crimes under international law, including by states that exercise universal jurisdiction."
New York-based Human Rights Watch (HRW) echoed this.
"Iranian authorities paved the way for Ebrahim Raisi to become president through repression and an unfair election," Michael Page, deputy Middle East director at HRW, said in a statement.
"As head of Iran's repressive judiciary, Raisi oversaw some of the most heinous crimes in Iran's recent history, which deserve investigation and accountability rather than election to high office."