The spy, who claims that in 1977, he was given a blank cheque to kill deposed prime minister Zulfiqar Ali Bhutto, said it was impossible for death row convicts to carry out such assaults without the connivance of authorities. Bhutto was lodged in the Lahore jail at the time, after being deposed in a military coup.
Having served time in a number of Pakistani jails between 1976 and 1996 on charges of being an Indian spy, Elahi said convicts on death row are kept under very strict surveillance guided by stringent stipulations in that country.
"Such convicts are taken out of their cells for a walk only once a day for half an hour, and they are handcuffed. So it is impossible for a convict on death row to attack someone," Elahi, who has served time with Asif Ali Zardari, now the Pakistani president, told IANS.
Sarabjit, 49, who had been lodged in Pakistani prisons for over 22 years, suffered critical head injuries in an assault by four to five prisoners with bricks and prison plates in Kot Lakhpat Jail in Lahore Friday. He has gone into coma, and is under treatment at Jinnah Hospital, Lahore.
Pakistani authorities have registered complaints against two inmates, both death row convicts.
"The security is very tight, with several people guarding the convicts during the walk. No two death row convicts are taken out for walk at the same time. They are taken out turn by turn. Till one is locked in his cell, another convict waiting for the gallows is not allowed out," Elahi said.
The assertion by Pakistani officials that two death row convicts led the attack does not hold water, he said.
"It is neither possible for two death row convicts to attack Sarabjit together, nor is it possible for any such convict to attack Sarabjit, who also belongs to the same category," said Elahi, who still bears the scars of torture.
"I have no doubt the attack was pre-planned, and there was the connivance of Pakistani officials," he said.
Elahi said superintendents in Pakistani jails are all-powerful. He recalled that a jail superintendent had once inflicted burn injuries on him.
"Nobody can raise a finger against them. The Indian prisoners are tortured daily. During my long stay in Pakistani jails, the prisoners were really good to me, though jail officials were hostile."
Elahi, a spy of the late 1960s and 1970s, had twice crossed over to Pakistan - once via East Pakistan (now Bangladesh) and once through the western border.
The Kolkata-based Elahi also found it puzzling how the guards at the watch towers failed to notice such a group assault.
However, he said making knives out of the spoons was common and blades could also be obtained in Pakistani jails.