The Indian government also asked Pakistan to consider the option of transferring 49-year-old Sarabjit to India so that he can benefit from the best medical treatment available here.
Based on the most recent medical bulletin put out by doctors treating him, it is clear that his condition remains critical, Ministry of External Affairs said, adding that it "shares the anguish and concern of his family members, and our prayers will remain with them".
In a statement, the ministry said, "In view of the recent tragic events and present circumstances, we once again appeal to the Government of Pakistan to take a sympathetic and humanitarian view of this case, and release Sarabjit Singh."
It reiterated its demands that the attack on Sarabjit be thoroughly investigated to identify those who were responsible and to ensure that they are punished. MEA also noted that "it is the responsibility of the Government of Pakistan to ensure the safety and security of all Indian prisoners in their custody."
Meanwhile, the ministry said officials of the Indian High Commission are in touch with the medical authorities at Jinnah Hospital in Lahore and "we would like them to consider the option of transferring Sarabjit Singh to India so that he can benefit from the best medical treatment available here."
Earlier, Minister of State for Home R P N Singh said India is ready to provide full medical assistance to Sarabjit.
"It is our endeavour and we will do whatever is in our hands to make sure that all proper medical treatment is given to Sarabjit Singh -whether it is Pakistani doctors or medical experts from foreign countries. We are also ready to provide full medical assistance, if there is a need for any assistance from our side," he told reporters outside Parliament House.
Sarabjit sustained several injuries, including a skull fracture, when six prisoners attacked him in Kot Lakhpat Jail on Friday and doctors have said his chances of survival are slim.
He was hit on the head with bricks and grievously injured with sharp weapons. He is in a deep coma and on ventilator support in an intensive care unit of Jinnah Hospital.
He was convicted of alleged involvement in a string of bomb attacks in Punjab province that killed 14 people in 1990.
His mercy petitions were rejected by the courts and former President Pervez Musharraf.
The Pakistan People's Party-led government put off Sarabjit's execution for an indefinite period in 2008.
His family says he is the victim of mistaken identity and had inadvertently strayed across the border in an inebriated state.