The UN Special Rapporteur on extrajudicial and summary executions, Philip Alston, said in a statement that four juvenile offenders had been executed in the past two years, while death sentences against five other were "on hold".
The UN Special Rapporteur on extrajudicial and summary executions, Philip Alston, said in a statement that four juvenile offenders had been executed in the past two years, while death sentences against five other were "on hold".
"The execution of juveniles in Iran is completely unacceptable", Alston added.
"It is time for Iran to demonstrate that its commitment to international law involves concrete action, not just empty words," he said, calling on Tehran to "immediately commute" all death sentences imposed for crimes committed before the age of 18.
The campaign group, Human Rights Watch, stated this week that Iran "leads the world" in the execution of juveniles."
The UN expert insisted that Iran had made a "clear and unambiguous commitment" on the issue when it ratified the international Convention on the Rights of the Child in 1994.
Alston said he had examined a total of 15 cases where young offenders had faced a possible death penalty in Iran in the past two years. Two were acquitted, and one is under review.
Rights groups have also voiced concern about a sharp growth in the overall number of executions in Iran, which increased by 80 percent last year to 177, according to Human Rights Watch.
The US-based group said executions often follow secret trials that fail to meet minimum international standards.
It highlighted the case of an Iranian court that sentenced 10 men to death following a one-day trial in July 2006.
Alston and two other UN experts released a joint statement in January warning that convictions and death sentences in the case could not be justified "after trials that made a mockery of due process requirements."