ISLAMABAD - The authorities on Tuesday hanged Shafqat Hussain whose case triggered an international outcry because his lawyers said he was arrested as a juvenile and tortured into confessing to murder.

Shafqat Hussain was hanged to death at the Karachi Central Prison in the wee hours of Tuesday.

Shafqat was arrested and sentenced to death in 2004 for the kidnapping and involuntary murder of a seven-year-old boy who lived in a Karachi apartment building where Shafqat worked as a security guard.

All courts in the land had turned down his appeals and the Supreme Court threw out a review petition that was the first to raise the matter of Shafqat’s juvenility at the time of arrest, maintaining that this line of defence should have been introduced at the trial court level.

Nearly 200 people have been hanged since December, when a massacre by militants at a Peshawar school 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," legal aid group Justice Project Pakistan, which was representing Shafqat, said in a statement.

Country’s law does not allow the execution of someone arrested as a juvenile. State prosecutors said Shafqat was an adult working as a watchman when he was arrested.

Lawyers for Shafqat 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 has said he was 14; lawyers said the family did not keep records regarding Shafqat's birth.

David Griffiths, Amnesty International's South Asia research director, said the execution marked a "deeply sad day for Pakistan". "A man whose age remains disputed and whose conviction was built around torture has now paid with his life," he said. Police denied that Shafqat had been tortured.

"A competent court has gone through Shafqat's case at length and torture allegations were never proved," police spokesman Qamar Zaib Satti told Reuters.

"There are cigarette burns on his shoulder," his brother Manzoor told Reuters the day before Shafqat was hanged. "They also burnt his ankles with a heated rod. Those scars are still there."

Their mother said the family was too poor to pay the 30,000 rupees ($300) a private lawyer demanded to fight the case.

She could only afford one trip to visit her son, she said, and did not see him before he died.

While the moratorium on capital punishment was lifted in response to the militant attack, a Reuters investigation found that few of those executed had links to militancy.