Iran secretly executed a long-serving prisoner arrested for killing a man when he was a child in a breach of international law. Sajad Sanjari was hanged at Dizelabad jail in western Iran at dawn on Monday, but his family learnt of his fate only when they were called by a prison official to collect the body, Amnesty International said. Sanjari was arrested in 2010 when he was 15 after fatally stabbing a man. The teenager told police that he was acting in self-defence after the victim tried to rape him, but he was convicted of murder and sentenced to death two years later. He was scheduled to be executed five years later, but the punishment was postponed after an international outcry, the rights group said. It said the subsequent secret hanging was part of an increasing pattern in which condemned prisoners are executed with little or no notice, to limit the chances of a successful campaign to save their lives. The United Nations has repeatedly condemned Iran for executing child offenders, saying it was a breach of international law. Iran signed a UN deal banning the practice in 1968, which was ratified seven years later. The International Covenant on Civil and Political Rights says “the sentence of death shall not be imposed for crimes committed by persons below 18 years of age” or pregnant women. Iran is the only country in the world to carry out such executions, according to Amnesty, which has recorded at least 95 executions since 2005 of convicted child criminals, but said the numbers was likely to be higher. “With the secret execution of Sajad Sanjari, the Iranian authorities have yet again demonstrated the utter cruelty of their juvenile justice system,” said Diana Eltahawy, its deputy director for the Middle East and North Africa. “The use of the death penalty against people who were under 18 at the time of the crime is absolutely prohibited under international law, and constitutes a cruel assault on child rights.” Amnesty says it has identified more than 80 people held on death row in Iran for crimes committed when they were children. They include Hossein Shahbazi who was convicted of murder committed when he was 17 at a trial that used a torture-tainted confession. He was convicted of killing a classmate in a mass brawl. He was due to be hanged in June but the sentence was not carried out after an international appeal for clemency. After his case was publicised, prison guards told Shahbazi, now 20, that the victim’s family would be contacted to request a pardon. The UN High Commissioner for Human Rights, Michelle Bachelet, said last year that numerous UN bodies and experts had made it clear “time and again” that the death penalty for crimes committed by children was strictly prohibited. She called on Iran to honour its international human rights obligations and halt all executions of juvenile offenders.