A Pakistani prisoner, who was critically injured after he was attacked by a fellow prisoner at a high-security prison in Indian-administered Kashmir, died in a hospital on Thursday.

Sanaullah Haq, aka Sanaullah Ranjay, who was in a coma, died of multi-organ failure at a hospital in India's Chandigarh city early on Thursday, news reports said citing doctors.

Haq was attacked by a fellow prisoner, who is a former soldier of the Indian Army convicted of murder, in Kot Bhalwal jail on the outskirts of northern Indian state of Jammu, in what appears to be a retaliatory attack against the death of Sarabjit Singh, an Indian man convicted of spying by a Pakistani court who died on May 2 following injuries inflicted in a brutal attack in a jail in Lahore.

“Although it's scant consolation I'd like to offer a sincere apology to the family of Sanaullah Haq and my sympathies for their loss,” Omar Abdullah, the chief minister of Jammu and Kashmir state, where Haq had been imprisoned since 1999, wrote on Twitter on Thursday.

“While the inquiry will fix responsibility for any dereliction of duty the fact that this happening at all is a matter of great regret,” he wrote.

Haq was convicted of a 1990s bomb attack that killed 10 people, according to a Reuters news agency report. Photos from jail show him sporting a long orange beard and a red coat, playing bagpipes for the prison band.

Pakistan has requested India to make arrangements to send his body back, NDTV news reported.

India’s Home Minister Sushil Kumar Shinde told the Press Trust of India (PTI) that Sanaullah's body will be handed over to Pakistan. Indian Ministry of External Affairs is coordinating with Pakistani authorities to complete formalities.

Last week, Pakistan High Commission in New Delhi said the “condemnable” assault was an “obvious retaliation to the death of Indian prisoner Sarabjit Singh” and called upon the Indian government “to investigate the matter thoroughly and punish the perpetrators of this atrocity.”

India said it regretted the incident, adding that it happened after an altercation. The jail superintendent was suspended and an inquiry is ongoing. The alleged attacker has been arrested and remanded to judicial custody.

Pakistani High Commissioner, Salman Bashir, in a meeting with Indian officials in New Delhi on May 3, said more than 50 Pakistani prisoners held in India had completed their sentences and should be released immediately, Pakistan’s Geo TV reported.

Bashir had visited Haq at the Chandigarh hospital on May 6. Two of his relatives had arrived from Pakistan on May 7 and visited the prisoner.

India’s Supreme Court on Wednesday expressed concern over the attack and issued notice to the central and the state government, asking them to explain why steps were not taken to prevent it.

The court was hearing a petition filed by Jammu and Kashmir Panthers Party chief Bhim Singh, seeking repatriation of foreign and Pakistani prisoners, including Sanaullah, and those who have spent more than 15 years in detention in the country.