"Particularly regrettable that the Govt of Pakistan did not heed the pleas.... to take a humanitarian view of this case," tweeted Manmohan Singh after Sarabjit Singh died Thursday in Lahore's Jinnah hospital.
Sarabjit Singh was viciously attacked by fellow prisoners April 26 in Lahore's Kot Lakhpat jail.
"May his soul be granted the peace that he could not enjoy in life. The nation shares his family's profound grief with them," said another tweet.
A third tweet said that the government "will make the arrangements to bring his remains home and for his last rites to be conducted in consultation with his family".
He also tweeted that the "criminals responsible for the barbaric and murderous attack on Sarabjit Singh must be brought to justice".