Mehdi Sohrabifar and Amin Sedaghat were executed on April 25 at the Adelabad prison in Shiraz, the capital of the southern Fars Province. The two had been arrested at age 15 and convicted on multiple rape charges after what international rights groups said was an unfair trial.

"I am appalled," Bachelet said in a statement on May 3, urging Tehran to immediately halt all executions of people accused of committing crimes while children.

"The prohibition of executions of child offenders is absolute under the International Covenant on Civil and Political Rights and under the Convention on the Rights of the Child," she said.

Iran is party to both treaties.

Bachelet said the cases of Sohrabifar and Sedaghat were particularly deplorable since "both boys were reportedly subjected to ill-treatment and a flawed legal process."

Amnesty International has recorded 97 executions of people under the age of 18 in Iran between 1990 and 2018.

With reporting by AFP