"We have learnt with deep concern that Sanaullah, who was serving life imprisonment in a jail (in Jammu and Kashmir), was attacked this morning and as a result has received grievous injuries," Foreign Office spokesman Aizaz Ahmad Chaudhry said.
"We would also remind the government of India of its responsibility in ensuring the safety and security of all Pakistani prisoners lodged in Indian jails," Chaudhry said.
The Indian government should take "all measures to ensure that Sanaullah receives the best medical treatment available, investigate the matter thoroughly and punish the perpetrators of this atrocity", he added.
Chaudhry described the attack on Sanaullah as an "obvious retaliation to the death of Indian prisoner Sarabjit Singh" and said it was "condemnable".
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Indian death row convict Sarabjit died yesterday of severe injuries sustained in an attack by other inmates of Lahore's Kot Lakhpat Jail on April 26. He had been comatose for almost a week after the brutal assault.
His family says he was the victim of mistaken identity and had mistakenly strayed across the border in an inebriated state. Pakistani rights activists too had called for the reopening of his case.