A 26-year-old Iranian woman convicted of murdering a man she accused of trying to rape her as a teenager was hanged on Saturday, the official news agency IRNA said, despite international pleas for her life to be spared.

Reyhaneh Jabbari walked to the gallows at dawn on Saturday in Tehran's Evin prison after failing to secure a reprieve from the murder victim's relatives within the 10-day deadline set by sharia law in force since the 1979 Islamic Revolution.

The death sentence sparked U.S. and European Union condemnation and the government of President Hassan Rouhani, who won election last year on promises of liberal reform at home and easing Iran's isolation abroad, to intervene to get it commuted.

Justice Minister Mostafa Pour-Mohammadi said in early October that a "good ending" was in sight, but official media reported later that the slain man's family could not be persuaded to approve leniency for Jabbari.

Jabbari was sentenced to death in accordance with Koranic "qisas", or eye for an eye, law after being found guilty of stabbing dead an older man with a kitchen knife in 2007.

She had pleaded self-defence but failed to sway judges at various stages of appeal up to Iran's Supreme Court and she remained in prison throughout.

Jabbari's last chance of reprieve lay with clerical Supreme leader Ayatollah Ali Khamenei, whose powers transcend all state mandates. But Khamenei never mentioned the case and has only rarely intervened in court cases regardless of political considerations.

Immediately after Saturday's execution, the Tehran state prosecutor's office issued a statement that appeared aimed at countering sympathy for Jabbari.

"Jabbari had repeatedly confessed to premeditated murder, then tried to divert the case from its course by inventing the rape charge," said the statement carried by IRNA.

"But all her efforts to feign innocence were proven false in various phases of prosecution. Evidence was firm. She had informed a friend through text message of her intention to kill. It was ascertained that she had purchased the murder weapon, a kitchen knife, two days before committing murder."

"Deeply Flawed Trial", Says Amnesty

London-based Amnesty International condemned the execution after what it called "a deeply flawed investigation and trial".

“This is another bloody stain on Iran’s human rights record,” Hassiba Hadj Sahraoui, Amnesty International’s Deputy Director for the Middle East and North Africa regions, said in a statement. “Tragically, this case is far from uncommon. Once again Iran has insisted on applying the death penalty despite serious concerns over the fairness of the trial.”

U.N. Secretary-General Ban Ki-moon has expressed alarm at a reported increase in executions in Iran which according to Amnesty has the second highest rate of capital punishment in the world, after China.

The U.S.-based Iran Human Rights Documentation Center put the total number of executions at 531 for this year, as of Sept. 30.

Jabbari's hanging comes at a bad time for Rouhani, who has been treading a precarious path to rapprochement with the West after decades of mutual hostility largely rooted in Iran's disputed nuclear program and human rights practices.

Rouhani has come under fire from secular Iranians, his main political constituency, over a spate of acid attacks on young women deemed by their attackers to have insufficiently covered their hair in accordance with sharia.

Many Iranians believe the vigilante assaults have been provoked by conservative hardliners in a continuing campaign to thwart the political and social reform agenda pledged by Rouhani during his 2013 election campaign.

But many of Iran's more secular voters have also voiced frustration that domestic reforms appear to have taken a back seat to foreign policy under Rouhani, in particular the tortuous negotiations with world powers to resolve the nuclear stand-off.

Rights activists and other critics fear that hardliners – particularly in the judiciary and elite Revolutionary Guards - who oppose Rouhani and his policy of conciliation with the West are pushing the executions to discredit him.

Reuters