Amnesty International is demanding that Iranian authorities cancel plans to hang a man a second time after he survived a first hanging.
The 37-year-old prisoner, identified only as "Alireza M," was hanged in Bojnourd prison in northeast Iran last week for drug crimes.
Reports say a doctor pronounced him dead, but he was found, alive, in a morgue the next day and was taken to a hospital, where he is recovering.
Philip Luther, director of Amnesty International's Middle East and North Africa program, said a second execution attempt would be "ghastly" and "betrays a basic lack of humanity that sadly underpins much of Iran's justice system."
According to the London-based rights group, Iran has executed at least 508 people so far this year.