The Justice Project Pakistan (JPP), a human rights law firm representing Shafqat Hussain, said the Supreme Court in the capital Islamabad would hear its appeal against an earlier court decision that rejected an inquiry into the case.

The Supreme Court adjourned the hearing until Wednesday.

It was the fourth time that Hussain, whose age is disputed, has had his death penalty postponed, and came hours before he was due to be hanged in the southern port city of Karachi.

A JPP spokesman said that on this occasion, Hussain would have been changed into white clothes and moved to a different part of the prison in preparation for his execution.

"Each time he has to say goodbye to his brothers. He has to go through this over and over again," the spokesman said.

Hussain's lawyers say he was just 14 in 2004 when he was burnt with cigarettes and had fingernails removed until he confessed to the killing of a child, a case that has angered rights groups and prompted mercy appeals from his family.

The authorities say that he was 23 when he was sentenced.

In addition to the legal appeal being heard in the Supreme Court, the JPP and one of Hussain's brothers filed a 22-page appeal to President Mamnoon Hussain urging him to grant "permanent clemency or pardon from execution".

Hussain is one of more than 8,000 people being held on death row in Pakistan, according to the human rights group Reprieve, the largest number of any country.

According to the group, around 150 people have been executed in Pakistan since mid-December, when Prime Minister Nawaz Sharif lifted a moratorium on the death penalty.

His decision came a day after Taliban militants attacked a school killing more than 130 pupils and 19 adults.