Daughters of a Pakistani man killed in the 1991 bomb blast blamed on Sarabjit Singh, have threatened to fast unto death if the Indian prisoner, who is due to be hanged on May 1, is pardoned.

Coverage: The Sarabjit Saga

The family of Singh, who was handed down capital punishment for his alleged involvement in bomb attacks in Lahore [Images] and Multan, has been camping in the country hoping to meet top leaders to seek clemency for him.

"The rulers would be responsible for the severe consequences as a result of the hunger strike," a daughter of deceased Nawaz Fazl said.

Fazl was travelling in the passenger train that hit by the blast on July 3, 1991

The woman, who was three-year-old at the time of the blast, said that that her two sisters would also start the hunger strike if the government pardoned Singh.

Gulzar [Images] Ahmed Fazl, the brother of Nawaz Fazl, demanded that Sarabjit Singh be executed at the earliest and asked former human rights minister Ansar Burney not to make any effort for the release of 'terrorists' like Singh, the Daily Times reported.

Hundreds of students held a rally in Lahore on Friday demanding that the Singh not be pardoned.

The demonstrators termed former Pakistani human rights minister Ansar Burney, who has sent a mercy petition on behalf of Sarabjit to President Pervez Musharraf [Images], an 'Indian agent', The News daily reported.

The students said if Sarabjit is released, they would launch a joint movement against the government.

Tulaba Jamaatud Dawah chief Muzammil Iqbal Hashmi demanded that Burney should be arrested and tried for treason. He said the release of Sarabjit would 'humiliate' the whole nation.