A Pakistani prisoner suffered serious head injuries on Friday after being attacked in an Indian jail in apparent tit-for-tat violence following the death of an Indian inmate Sarabjit Singh in Kot Lakhpat Jail in Lahore, a prison official said. “He has been admitted in GMC Hospital with grievous head injuries,” an official at the main prison in Jammu said. The prisoner, named as Sanaullah, was attacked early in the morning by other inmates, the official said, a day after India's home ministry ordered stepped-up security for hundreds of Pakistanis in Indian prisons.