Attari (Amritsar): The heart and stomach of Indian prisoner Kirpal Singh, who died under mysterious circumstances in a Pakistani jail, were found missing after his body was handed over to Indian authorities.

"During the postmortem, it was found that his heart as well as stomach were missing. However, no internal and external injury was found on his body. Samples of these two organs would be sent outside Amritsar for laboratory tests to bring out more facts with regard to his death," Principal of Government Medical College Amritsar, Dr BS Bal said.

Meanwhile, Kirpal's family has alleged that he was tortured to death and that he did not die of cardiac arrest as has been told by Pakistan.

Kirpal's family members, including his sister Jagir Kaur, Punjab Cabinet Minister Gulzar Singh Ranike and Amritsar Deputy Commissioner Varun Roojam, besides other senior officials, were present at the Joint check post at the Wagah border to receive the body on Tuesday.

Dalbir Kaur, sister of another Indian Sarabjit Singh who died in a Pakistani jail in May 2013, was also present. She said, "even if he died from a heart attack, there must be some reason behind it. His body should be sent for examination, the matter should be investigated. I don't believe it's a natural death."

Kirpal Singh had allegedly crossed Wagah border into Pakistan in 1992 and was arrested. He was subsequently sentenced to death in a serial bomb blasts case in Pakistan's Punjab province.

Kirpal was found dead in his cell last Monday at Kot Lakhpat Jail in Lahore.

Kirpal, from Gurdaspur, had reportedly been acquitted in the case by the Lahore High Court but his death sentence could not be commuted because of unspecified reasons.