Gujarat Chief Minister Narendra Modi slammed the Indian government over its handling of Mr Singh's case with Pakistan.
"Sarabjit Singh's extra-judicial killing is yet another grim reminder that expecting Pakistan to follow due process of law in any sphere is futile. The Centre is unable to give a strong answer to Pakistan's inhuman acts. The beheading of our soldiers and now Sarabjit's death are two recent examples," Mr Modi said at an election rally in Mangalore.
Mr Singh died at 12.45 am on Thursday at the Jinnah hospital in Lahore, where he was admitted after being savagely attacked by a group of inmates in jail last Friday. Mr Singh had been in a coma and on ventilator support since then.
Ms Swaraj is expected to meet Mr Singh's family in New Delhi in a short while from now.
Home Minister Sushil Kumar Shinde visited them early this morning and assured them that the government would do its utmost to bring back Sarabjit's body to India at the soonest. The Indian government too has in a strong statement, said, "It was simply killing of our citizen in jail...we demand that the government of Pakistan conduct a thorough investigation to identify those are guilty."
Prime Minister Manmohan Singh while expressing grief, said "It is particularly regrettable that the government of Pakistan did not heed the pleas of the government of India, Sarabjit's family and of civil society in India and Pakistan to take a humanitarian view of this case."
Ms Swaraj's party colleague Gujarat Chief Minister Narendra Modi has slammed the Centre tweeting, "Centre is unable to give a strong answer to Pakistan's inhuman acts. Beheading of our soldiers & now Sarabjit's death are 2 recent examples."
He also tweeted "Both, the Government of India & Government of Pakistan have misled people on Sarabjit Singh issue. The truth on this issue must come out," minutes after his first Tweet that said, "Sarabjit Singh's demise is very sad. May his soul rest in peace. May God give strength to his family to bear this loss."