According to sources, Sarabjit's attackers, a group of six prisoners, were being held in a barrack near Sarabjit's barrack in one of the most secure sections of Kot Lakhpat Jail.
The prisoners gathered near Sarabjit's barrack and overpowered two jail wardens. Meanwhile, the main accused Aftab snatched the key of Sarabjit's cell and opened the door, said sources.
Sarabjit reportedly was hit on the head with bricks and his face, neck and stomach were cut with blades and sharp pieces of a ghee tin.
Jail officials were quoted as saying, "When the staff found Singh, he was unconscious and bleeding profusely. The staff removed his clothes which were covered with blood. They put on the shirt and pants of a jail warden and took him to Jinnah Hospital."
Pakistan police on Saturday, April 27 filed a case of attempted murder against two prisoners for brutally assaulting Sarabjit. The FIR was registered following a complaint from assistant superintendent Ishtiaq Ahmed Gill of Kot Lakhpath Jail.
The two accused have been booked under sections 324 (attempted murder) and 334 (causing severe injuries) of the Pakistan Penal Code.
Sarabjit was convicted for alleged involvement in a string of bomb attacks in Punjab province that killed 14 people in 1990. His mercy petitions were rejected by the courts and former President Pervez Musharraf.
The outgoing Pakistan Peoples Party-led government put off Sarabjit's execution for an indefinite period in 2008. Sarabjit's family says he is the victim of mistaken identity and had inadvertently strayed across the border in an inebriated state.