An international human rights group has called on Iran to stop executing people under the age of 18, saying the country leads the world in the practice.

Human Rights Watch said Iran had executed at least 17 juvenile offenders, eight times more than any other country, since the beginning of 2004, including two so far this year.

"Iran holds the deplorable distinction of leading the world in juvenile executions, and the authorities should end this practice at once," Clarisa Bencomo, HRW's Mideast children's rights researcher, said in a statement issued Wednesday.

Iranian officials could not immediately be reached for comment.

Such sentences violate international treaties ratified by Iran that prohibit the death penalty for crimes committed by people under the age of 18, according to the human rights group.

It said Iran's judiciary had repeatedly upheld death sentences for juveniles charged with committing crimes when they were as young as 15.

"The Iranian government needs to stop sending children to the gallows and start living up to its international obligations by issuing clear legislation to ban the juvenile death penalty," said Bencomo.

Tehran's judiciary chief Alireza Avaii has said no juvenile executions have taken place in Iran in "a long time," the human rights group said. Iranian officials also have indicated the Parliament is working to establish a set of juvenile courts that would end the practice in the country, it added.

But HRW said the new legal framework would still allow the death penalty for juvenile offenders if the judge decided the defendant was "mentally mature." The group called on the Iranian Parliament to remove this legal discretion.

According to a combination of documents obtained by HRW and press accounts, the rights group said Iran had executed two juvenile offenders since the beginning of 2007. Syed Mohammad Reza Mousavi Shirazi, 20, was executed on April 22 for a murder he allegedly committed when he was 16, and Sa'id Qanbar Zahi, 17, was put to death on May 27, although the statement did not report his alleged crime.

HRW said Iran had executed at least three juvenile offenders in 2004, eight in 2005 and four in 2006.

Sudan, China and Pakistan are the only other countries known to execute juvenile offenders, according to the release. It said China is the only nation to execute more people, including both adults and children, than Iran annually, but Tehran ranks higher on a per capita basis.