

The state ruled Wednesday that the seven should be released because they have served more than 20 years in prison. Critics immediately slammed the decision, calling it a transparent attempt to win over Tamil voters in this year's national elections.

The federal government petitioned the Supreme Court on Thursday to stop the state from freeing the prisoners, with Prime Minister Manmohan Singh saying the move was "not legally tenable."

The court on Tuesday had commuted the death sentences for three of the convicts, after their lawyers argued that executing them now, after they had already served long prison terms, would amount to an unconstitutional double punishment.

Rakesh Dwivedi, a lawyer for Tamil Nadu's government, said the court's order Thursday applied only to the three prisoners whose sentences had been commuted, and that the state was free to release the other four.

The court asked the federal government to file a separate petition regarding the fate of the four prisoners not covered by Thursday's decision, the Press Trust of India news agency reported.

Gandhi, 47, was killed by an ethnic Tamil suicide bomber in Tamil Nadu in May 1991 as he campaigned for a return to the post of prime minister. Sixteen other people were killed in the attack.

The assassination was orchestrated by Sri Lanka's Tamil Tiger rebels to avenge Gandhi's decision to send Indian troops to intervene in the country's civil war in the 1980s.

Mohan Parasaran, the solicitor-general who argued the federal government's petition on Thursday against the release of the convicts, said he told the Supreme Court that the state government had no authority to free the prisoners.

"The appropriate government to consider the grant of remission to prisoners is the federal government," he told reporters.

The court scheduled further arguments in the case to be heard on March 6, and the state is unlikely to release any of the seven prisoners—six men and one woman—before then.

Tamil Nadu's government ruled Wednesday that the seven should be released because they have served more than 20 years in prison. Jayaram Jayalalitha, the state's top elected official, said if the federal government failed to respond to the decision within three days, she would release all of them on her own.

The issue triggered noisy scenes when the lower house of India's Parliament met Thursday, with lawmakers from the ruling Congress Party strongly protesting the state's decision. The speaker adjourned the session for an hour to cool the tempers.

Prior to the Supreme Court's ruling, Prime Minister Singh formally asked the state not to free the convicts.

"We have informed the Tamil Nadu government that their proposed course of action to release the killers of Rajiv Gandhi is not legally tenable and should not be proceeded with," Singh said in a statement to the media.

He said Gandhi's assassination was "an attack on the soul of India."

"No government or party should be soft in our fight against terrorism," the statement said.

Rahul Gandhi, the son of Rajiv Gandhi and Congress Party vice president, said he was opposed to hanging the convicts, but criticized the state's decision to free them. His mother and the Congress party chief, Sonia Gandhi, said in 1999 that nobody should be hanged in the case.

The seven convicts, who were among 26 people convicted of playing minor roles in the plot to kill Gandhi, are the only ones still in prison for the assassination. Some others died in prison or were released.

While the convicts have been reviled across much of India, many ethnic Tamils in the south believe they were duped into taking part in a plot they knew little about. The people of Tamil Nadu have a strong affinity with Tamils living in northern Sri Lanka.

With Indian national elections due to be held by May, two powerful state parties led by Jayalalitha and her rival, Muthuvel Karunanidhi, are eager to gain the support of Tamils sympathetic to the cause of Tamil separatists in Sri Lanka. 

Rajiv Gandhi's mother, Indira Gandhi, was assassinated while prime minister in 1984 by her Sikh bodyguards after she ordered the Indian army into the Sikhs' holiest shrine in the northern city of Amritsar to stamp out a separatist campaign.