LAHORE: Sarabjit Singh, an Indian national on death row in Pakistan, who was attacked by fellow inmates armed with bricks has been put on a ventilator as he fights for his life, officials said on Saturday.

Singh, who was sentenced to death 16 years ago on espionage charges, was rushed to hospital on Friday with multiple wounds, including a severe head injury, after an argument in Lahore's Kot Lakhpat Jail.

“Singh's condition is critical with multiple wounds on his head, abdomen, jaws and other body parts, and he has been put on ventilator,” a senior doctor in Lahore's Jinnah hospital told AFP on condition of anonymity.

Singh is fighting for his life in the hospital's intensive care unit (ICU), and the next 24 hours are critical, the doctor said, adding that the head injury was “quite severe”.

“He needs surgery but the doctors are not performing it because they don't want to take any chances and want him to stabilise,” he said.

Singh was hit with bricks and other blunt objects by two inmates, a police officer investigating the case told AFP, identifying the suspects only by single names Aamir and Mudasir.

“These inmates attacked Singh while he was doing his evening walk. We don't exactly know at the moment what was the reason for this attack but initial investigation reveals that they had exchanged hot words with Singh,” he said on condition of anonymity.

Singh's lawyer Owais Sheikh told AFP his client had received threats following the execution of a Kashmiri separatist in India. Mohammed Afzal Guru was hanged in New Delhi on February 9 for his part in a deadly attack on the Indian parliament in 2001.

The Human Rights Commission of Pakistan (HRCP) condemned the attack as a “dastardly act” and called on the government to make a thorough inquiry into the matter and punish the guilty persons.

“The authorities have obviously failed to do their elementary duty” of providing him safety and security, the commission said in a statement.

Singh's sister, Dalbir Kaur, said Indian government officials had told her that Pakistan has granted visas for four family members to travel to Lahore and is also allowing one person to stay with him in the hospital.

“We want to be with Sarabjit in this difficult time. He is all alone. We don't even know what his condition is,” Kaur told AFP in Amritsar.

Singh was arrested following a bombing in Lahore in 1990 in which 14 people were killed.

He was sentenced to death after being convicted by a Pakistani court on spying charges.

His family has filed mercy petitions to Pakistani authorities seeking Singh's release.

Pakistan maintains he was an Indian spy, but Singh's family say he is a farmer who accidentally crossed the border into Pakistan while drunk.