Last week, the Supreme Court stayed the release of Murugan, Santhan and Perarivalan.
The Supreme Court today decided to hear the Centre's plea on Thursday challenging the Tamil Nadu government's announcement to release the assassins of former Prime Minister Rajiv Gandhi.
A top court bench headed by Chief Justice P Sathasivam agreed to hear the plea after Additional Solicitor General Siddharth Luthra told the court the Tamil Nadu government had no jurisdiction to release the conspirators.
Last week, on a petition by the Centre, the Supreme Court stayed the release of three of seven convicts - Murugan, Santhan and Perarivalan - whose death sentence was commuted because of an exceptional delay in a decision on their mercy plea.
The Tamil Nadu government claimed that the court had not stopped it from releasing the four other convicts, Murugan's wife Nalini Sriharan, Robert Pious, Jayakumar and Ravichandran.
Less than 24 hours after the top court commuted the death sentence of the three convicts, Ms Jayalalithaa announced that all seven convicts in the case would be freed. On Thursday last week, she asked the Centre to give its views "within three days", after which, she said, she would go ahead.
Prime Minister Manmohan Singh said last week that letting off the convicts would be contrary to all principles of justice as Rajiv Gandhi's assassination was "an attack on the soul of India."
The convicts have spent over 20 years in jail. Nalini, who was earlier on death row, was granted mercy on the intervention of Rajiv Gandhi's widow and Congress president Sonia Gandhi.
Rajiv Gandhi was assassinated in 1991 by a woman operative of the Lankan Tamil separatist outfit LTTE, who greeted him with a bomb strapped to her chest during a rally in Sriperumbudur in Tamil Nadu. For years, the case has been linked to Tamil sentiment and all regional parties in the state have campaigned for the convicts' release.