Chief Minister Jayalalithaa's cabinet met this morning and decided to free the convicts a day after the Supreme Court left it to the state to grant them remission. The state government, however, has to consider the Centre's views.
The convicts have been in jail for 23 years.
Nalini Sriharan, the wife of convict Murugan, was granted mercy in 2000 on the intervention of Rajiv Gandhi's widow, Congress president Sonia Gandhi.
The top court had yesterday spared Murugan, Santhan and Perarivalan from execution, citing the 11-year delay in a decision on their mercy plea. The court rejected the government's view that the convicts did not deserve mercy as they had shown no remorse and there was "no agony, torture or dehumanizing effect due to the delay."
The largely pro-Lankan Tamil sentiment in the state gave a political twist to the assassination case, which has been inextricably linked to Tamil Nadu's electoral politics over the years. All parties have joined calls for the convicts' release; even Congress politicians from the state have not opposed it.
"I am not unhappy," union minister P Chidambaram, who is from Tamil Nadu, told NDTV. "Our grief at Rajiv Gandhi's loss is irreparable. The court made it possible. I do not see this as cynical politics." He sought to blame the previous BJP-led government at the Centre for sitting on their mercy petition for four years.
Jayalalithaa's rival Karunanidhi of the DMK said, "It's not a prompt decision by the state government. They ridiculed me when I proposed their release." (Read: Who said what)
Santhan, Murugan, Perarivalan and the others were convicted in 1998 for Mr Gandhi's assassination by a woman operative of the Lankan Tamil separatist outfit LTTE, who greeted the Congress leader with a sandalwood garland and a bomb strapped to her chest during a rally in 1991.
Their hanging was stayed in 2011 on the orders of the Madras High Court. That year, the Tamil Nadu assembly passed a resolution urging the President to grant mercy to the convicts and consider "Tamil sentiment."