A Christian death row convict Aftab Bahadur Masih was executed on Wednesday morning in Kot Lakhpat Jail of Lahore in Pakistan, officials said.
"Aftab Bahadur was hanged at District Jail Lahore on Wednesday at 4.30 a.m.," a prison official told Reuters on the condition of anonymity.
"Before the hanging, he was crying and saying he was innocent," the official said when describing Masih's reaction before the hanging.
Masih's hanging took place even as a last-minute reprieve was granted to another death row convict Shafqat Hussain, reported The Telegraph.
Masih spent 23 years in prison after being convicted of killing three people in 1992. Rights groups claimed that he was tortured into confessing to the crime.
British rights group Reprieve and Justice Project Pakistan, a law firm handling Masih's case, said that Masih was just 15 when he supposedly committed the murders and too young to face the death penalty, according to AFP.
"This is a truely shameful day for Pakistan's Justice System," Maya Foa of Reprieve UK said in a statement.
"Aftab was subjected to almost every injustice conceivable. Just 15 years old when he was arrested, tortured and sentenced to death, he spent 23 years languishing on death row for a crime he didn't commit before being executed in the early hours of this morning," Foa said.
"To the last, Pakistan refused even to grant his lawyers the few days needed to present evidence which would have proved his innocence. This is a travesty of justice, and tragedy for all those who know Aftab," she said.
Masih wrote an essay from his cell, published by The Guardian a day before his execution.
"I just received my Black Warrant. It says I will be hanged by the neck until dead on Wednesday, 10 June. I am innocent, but I do not know whether that will make any difference," he wrote in a moving essay.
"During last 22 years of my imprisonment, I have received death warrants many times. It is strange, but I cannot even tell you how many times I have been told that I am about to die," Masih wrote.
A moratorium on the executions lifted in December last year after the massacre of 132 school children in Peshawar.
Pakistan has over 8,000 death row prisoners, the largest in the world, according to Justice Project Pakistan. More than 130 people have received the death penalty in 2015.
