France on Monday condemned Iran over the executions this month of two young offenders who it said where minors at the time of their crimes, accusing Tehran of violating its international obligations.

The French foreign ministry said that Shayan Saeedpour was executed on April 21 and Majid Esmailzadeh on April 18, noting they were both "minors at the time of the facts".

"The executions are contrary to the international obligations that Iran has signed up to itself, in particular the international convention on the rights of the child," it said.

Amnesty International had already condemned the execution of Saeedpour, 21, at the central prison in Saqqez, in Iran's Kurdistan province, "as vengeful and cruel."

It said the conviction was in connection with the fatal stabbing of a man during a fight in August 2015 when Saeedpour was 17. He had a history of mental illness.

It said Saeedpour was among dozens of prisoners who had escaped from the central prison in Saqez in late March amid riots over Iran's response to the coronavirus outbreak and fears it could spread to prisons.

Amnesty said it "believes his execution may have been an act of retaliation by the local prosecution authorities, intended to deter other prisoners from attempting similar escape plans."

Reports said that Majid Esmailzadeh was executed in Ardabil prison in the northern Ardabil Province.

UN High Commissioner for Human Rights Michelle Bachelet had already condemned both executions as "absolutely prohibited under international human rights law."

The French statement also "expressed concern" over reports that another young offender, Danial Zeinolabedini, who had also been condemned to death, had died in prison.

Amnesty has said Zeinolabedini, who was on death row for a crime committed when he was under the age of 18, died "under suspicious circumstances".

His family were told he had committed suicide but Amnesty said examination of a photograph of Zeinolabedini's body showed "signs that are consistent with torture."

Iran is one of the world's most prolific users of the death penalty, with Amnesty saying it carried out at least 251 executions in 2019.