"His name was given by Pakistan in the list of Indian prisoners. However, we have not been able to establish his identity on two occasions," External Affairs Minister spokesperson Syed Akbaruddin said here.
Talking about the two occasions, he said, one was during the visit of the judicial committee in April and the other during consular access this month as he was not in a mental condition to articulate any details about him.
Officials had said in Pakistan that an "Indian prisoner" died of a suspected heart attack in a hospital in Lahore.
Zakir Mumtaz, believed to be a resident of a village near Amritsar, was admitted to Jinnah hospital Wednesday after he fell ill, sources said.
Mumtaz, 50, was arrested on August 3, 2011 for allegedly crossing the border illegally.
He was held in a jail in Sheikhaupura before being sent to Kot Lakhpat jail in Lahore.