The flight took off from Chandigarh airport Thursday evening with the body.
"The body was handed over to officials of the Pakistan High Commission and formalities completed at the airport before the flight took off," an official said here.
A minor hiccup related to documentation and other formalities earlier held up the plane's departure, scheduled around 5 p.m. by over an hour, an official source said.
Sanaullah, who had been hospitalised at Chandigarh's PGIMER hospital after being attacked in Jammu's Kot Bhalwal jail May 3, died due to multiple organ failure, doctors said.
Flown to Chandigarh from Jammu last Friday after he was attacked, Sanaullah remained "extremely critical" and in "deep coma" in the last six days.
"Sanaullah was declared dead around 7 a.m. due to multiple organ failure. The team of doctors headed by Y.K. Batra tried their best to revive him," a spokesperson of the Post-Graduate Institute of Medical Education and Research (PGIMER) said.
Sanaullah had been in deep coma since the attack on him by a fellow inmate May 3, just a day after Sarabjit Singh, an Indian prisoner in Pakistan, succumbed to grievous injuries following a vicious assault in Lahore's Kot Lakhpat Jail.
Legal formalities were completed in coordination with the Jammu and Kashmir government as he was serving his life term in that state.
Chandigarh Home Secretary Anil Kumar had said Sanaullah's body would be air-lifted to Pakistan after his post-mortem and completion of other formalities.
Pakistan High Commission spokesperson Manzoor Ali Memon said in New Delhi that Pakistan was "in grief and shock".
"We have requested the government of India for an international inquiry into the brutal attack on the Pakistani citizen," Memon said.
In Islamabad, the Pakistan government demanded that perpetrators of this "heinous crime be brought to justice".
"We have learnt with a deep sense of grief that Sanaullah has expired today (Thursday) in a hospital in Chandigarh, India. He succumbed to the brutal injuries inflicted upon him during an attack in a jail," said the Pakistan ministry of foreign affairs.
India said all necessary measures, medically and otherwise, had been taken to save him.
"Unfortunately, despite our best efforts, he succumbed to the injuries and died in the hospital today," said ministry of external affairs (MEA) spokesperson Syed Akbaruddin.
Asked about Pakistan's demand for an international probe into the incident, he said India had already conveyed that the two countries should sit together and take forward the recommendations of a joint judicial panel.
Asked about Pakistan's demand for an international probe, union Home Minister Sushilkumar Shinde said: "I cannot comment on this now as no demand has come to us till now. When the demand comes, I will tell you."
As news came in about Sanaullah's death, 17 Pakistani prisoners lodged in the Jammu jail raised anti-India slogans.
Jammu and Kashmir Chief Minister Omar Abdullah offered his "sincere apology" to Sanaullah's family.
"Although it's scant consolation, I'd like to offer a sincere apology to the family," Abdullah tweeted.
The chief minister regretted that such a thing should have happened at all, but assured that those responsible for dereliction of duty in this incident would not go unpunished.
Two members of Sanaullah's family had arrived in Chandigarh Tuesday from Pakistan. They had appealed to the Indian government to repatriate him to Pakistan.
Sanaullah was arrested in 1996 and charged with involvement in a bomb blast at Katra near the Hindu shrine of Mata Vaishno Devi in 1994 which left 10 people dead. He was serving life term in the Jammu jail.
--IANS (Posted on 10-05-2013)