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Indians were outraged at the Pakistan government Thursday after a convicted Indian spy died from a head injury suffered when two inmates attacked him with a brick in a Pakistani prison last week.

Indian Prime Minister Manmohan Singh said his government would arrange to bring Sarabjit Singh's remains home and for his last rites to be conducted in consultation with his family. Singh in a statement called it "'particularly regrettable" that Pakistan did not heed pleas to take a humanitarian view of the prisoner's case and allow him to return after he had served 20 years in prison.

Singh was arrested in 1990 after bombings in Lahore and Faisalabad that killed 14 people. He was convicted of spying and carrying out the bomb blasts, and the death sentence he received was upheld in Pakistani superior courts.

His family maintained Singh was innocent and had entered Pakistan inadvertently from his hometown of Bhikiwind in northern Punjab state bordering Pakistan.

Singh was attacked Friday and taken to a hospital. He died early Friday at Jinnah Hospital in the eastern city of Lahore after being comatose and on a ventilator for the last few days, according to a Pakistani foreign office statement in Islamabad.

The Pakistan government was completing all formalities to hand over Singh's remains to the Indian high commission in Islamabad as early as possible, it said.

Singh's death is expected to affect the ties between the nuclear-armed rivals, which have fought three major wars since they achieved independence from Britain in 1947.

India's External Affairs Minister Salman Khurshid said Thursday that relations between India and Pakistan "have been hurt by this terrible tragedy."

Singh's sister Dalbir Kaur, who visited him in the Lahore hospital early this week, called for snapping of ties with Pakistan. "It's a murder by Pakistan."

Ravi Shankar Prasad, the main opposition Bharatiya Janata Party leader, slammed the Indian government and said he was "very pained by the gross indifference" by the Indian government in not putting enough pressure on Islamabad earlier to seek Singh's release.

Manish Tewari, India's information and broadcasting minister, said his government had been pressing Pakistan to release Singh since 2005.

India's ties with Pakistan have seen several ups and downs in recent years. The 2008 terror attack in Mumbai led to heightened tensions and brought the neighbors to the brink of war, but tensions eased after intense diplomatic pressure from the international community and a promise by then-Pakistani President Gen. Pervez Musharraf to clamp down on the militants.

Relations warmed somewhat in recent years, especially with regard to trade.

However, the ties deteriorated again after border clashes between their two armies early this year in which three Pakistani soldiers and two Indian soldiers were killed. The deaths ratcheted up tensions in an area where the two countries have long battled for dominance.

External Affairs Ministry spokesman Syed Akbaruddin said India was demanding a thorough investigation to identify who was responsible for the attack.

"This was simply the killing of an Indian citizen while in the custody of Pakistani authorities," the statement said. The attack "highlights the need for a concerted action by Pakistan to safeguard Indian prisoners in Pakistan."