Iranian judiciary chief Ayatollah Mahmoud Hashemi Shahroudi has approved the death sentence for a man who committed murder at the age of 17, Fars news agency reported on Tuesday.
Saeed Jazi, who had stabbed a man to death in 2003, will be hanged soon if the victim's family does not pardon him, Fars said.
"The qisas [execution] verdict was sent to the judiciary chief's office to ask for permission. It was approved by Ayatollah Shahroudi," Fars said.
Jazi had got into a fight with the victim, who worked at his friend's deli, over snatching a sandwich from the counter. The victim called him names and punched him in the mouth, the report said.
Rights activists have sought to raise the age of legal responsibility in Iran's Islamic law, which deems a boy punishable from the age of 15 and a girl from the age of nine.
The European Union and international human rights groups have been pressuring Iran to stop executing those under age 18, and the UN General Assembly has adopted a non-binding resolution denouncing the practice of executing minors in Iran.
Iran's conservative judiciary maintains that minors are not executed in the Islamic republic, but in some cases murderers have been hanged after reaching the age of 18.
In Iran a murder victim's family has the right either to demand a murderer's execution or accept blood money. In some cases convicts manage to reach a financial settlement with the family.
According to the rights group of Nobel peace laureate Shirin Ebadi at least nine people were executed for crimes committed as minors in the past Iranian year to March 2008.