Islamabad, Apr 21: Former Pakistani Human Rights Minister Ansar Burney filed a mercy petition on behalf of Sarabjit Singh, an Indian prisoner on death row, to President Pervez Musharraf.

The Pakistan government had earlier made a proposal to President Musharraf to commute all death sentences on prisoners in that country into life imprisonment.

"We are extremely grateful to the Pakistan government for making this proposal. We are also very grateful to external affairs minister Pranab Mukherjee for making an appeal for Sarabjit," his sister Dalbir Kaur said.

"We thank Pakistan PM Yousuf Raza Gillani for taking up the cause of my brother," she added.

On Friday, India made a fresh appeal to Pakistan to show mercy to the "unfortunate human being" on humanitarian grounds. External Affairs Minister Pranab Mukherjee hoped clemency would be shown to Sarabjit who has been in a Pakistani jail since 1990.

Sarabjit was sentenced to death for his alleged involvement in four bomb blasts in Pakistan that killed 14 people.

He was originally set to be hanged on April 1. The execution was however deferred by a month by President Musharraf so that the new government could review the case. The hanging is currently set for May 1.