Sanaullah, who had been at the PGIMER hospital after his attack in Jammu's Kot Bhalwal jail May 3, died just before 8 am on Thursday.
"We are in deep grief and we are shocked. We express our deep condolences to Sanaullah's family and people of Pakistan for the brutal and extra judicial killing of the innocent citizen of Pakistan. The killing has taken place under the nose of Jammu and Kashmir jail authorities," Memon said.
The Pakistani had been in deep coma since he had been flown to Chandigarh from Jammu last Friday.
Sanaullah had suffered renal failure on Wednesday.
"There is a need for agreement of security and safety of prisoners in jail," Memon told a news channel in New Delhi.
The attack on Sanaullah took place a day after Sarabjit Singh, an Indian prisoner in Pakistan, succumbed to grievous injuries following a murderous assault in Lahore's Kot Lakhpat Jail.
Sanaullah was arrested in 1996 and charged with involvement in a bomb blast at Katra near the Hindu shrine of Mata Vaishno Devi in 1994 which left 10 people dead. He was serving life term in the Jammu jail.