ISLAMABAD: Pakistan today hanged a man whose case triggered an international outcry after his lawyers said he was arrested as a juvenile and tortured into confessing to a murder.

Pakistan has hanged nearly 200 people since December, when a massacre by Taliban militants at an army-run school in Peshawar prompted the government to lift a de facto ban on capital punishment.

Only Iran and China have executed more people than Pakistan this year, says human rights group Amnesty International.

"Shafqat Hussain was this morning executed in Pakistan, despite widespread calls, both within and outside the country, for a stay," the legal aid group Justice Project Pakistan, which was representing Hussain, said in a statement.

An official at the Karachi Central Jail, where the sentence was carried out, confirmed the execution.

Pakistani law does not allow the execution of someone arrested as a juvenile, but state prosecutors say Hussain was an adult working as a watchman when he was arrested.

Lawyers for Hussain said school records showed he was 17 in 2004 when he was burnt with cigarettes and had fingernails removed until he confessed to killing a child.

His family have said he was 14; lawyers said the family did not keep records regarding Hussain's birth.

"Why did they hang my innocent brother, only because we were poor?" said his sister Sumaira Bibi, beating her chest and weeping.

His mother Makhni Begum, looked glassy-eyed, stunned by the news of the execution after seeing her son reprieved from the gallows four times since January.

"My son was innocent, only Allah will prove his innocence in his court," she told.

United Nations rights experts have said Hussain's trial "fell short of international standards" and urged Pakistan not to hang him without investigating claims he confessed under torture, as well as his age.

Adding to the concerns, after receiving his body, Hussain's brothers claimed the hanging had not been carried out properly.

"There is a cut mark on his neck and half of his neck is separated from his body," brother Abdul Majeed told.

Supporters of the death penalty in Pakistan argue that it is the only effective way to deal with the scourge of militancy.