New Delhi, Aug 26 (IANS): The People's Union for Democratic Rights (PUDR) Friday urged the Tamil Nadu government to spare the lives of three men sentenced to death for former premier Rajiv Gandhi's assassination.

The PUDR was "deeply distressed" by President Pratibha Patil's rejection of the appeal for mercy from Santhan, Murugan and Perarivalan, awarded the death penalty in 1997. The Supreme Court upheld this in 1999.

"While the crime committed is heinous, there are a number of reasons that should permit commutation of their sentence to life imprisonment," it said in a statement.

The PUDR said the three have displayed exemplary conduct during their 20 years in prison.

It said Perarivalan had completed his Bachelor of Computer Application (BCA) and was pursuing further studies. He had helped educate many illiterate and semi-literate prisoners.

Murugan, formerly a Tamil Tiger intelligence activist, passed the BCA and MCA as well as certificate courses in Radio AND TV mechanics and two-wheeler engine mechanics. "He is a talented painter."

Santhan has written numerous poems, short stories and a novel. He also tends to the temple in the prison and conducts the daily prayers.

"Today there are large numbers of people in Tamil Nadu appealing to the government to spare the lives of these three prisoners.

"PUDR appeals to the governor and to the government of Tamil Nadu to show compassion in sparing the lives of the three prisoners.

"The killing of these three persons serves no social objective today. Sparing them would protect the citizens of our country from the ill-effects of promoting of revenge as a justifiable objective."

A woman suicide bomber assassinated Rajiv Gandhi at an election rally near Chennai May 21, 1991.