“I am extremely concerned that despite a stated moratorium of the Iranian Government on execution by stoning this execution has gone ahead,” Ms. Arbour said in a statement released in Geneva. “Stoning is in clear violation of international law, which also limits the death penalty to only the most serious, violent crimes.”

Jafar Kiani was reportedly stoned to death on 5 July in Takestan, in Iran’s Ghazvin Province, according to the statement.

Mr. Kiani, and his companion, Mokarrameh Ebrahimi, had reportedly been in prison for more than 11 years accused of adultery. The couple was originally scheduled to be killed by stoning on 21 June, but that execution was stayed.

“I urge the Iranian authorities to shed light on the reported execution and to stop the scheduled stoning of Mokarrameh Ebrahimi and all other such executions,” Ms. Arbour declared.

Iran is a party to the International Covenant on Civil and Political Rights, which states in article 6 that “in countries which have not abolished the death penalty, sentence of death may be imposed only for the most serious crimes.” Article 7 of the Covenant holds that, “No one shall be subjected to torture or to cruel, inhuman or degrading treatment or punishment.”