The government said this in its counter affidavit in response to a petition by Nalini seeking premature release.
The case is expected to come up before Justice M Sathyanrayanan on Monday.
Nalini submitted that she had spent quarter of a century in jail though the legal requirement was only 20 years to be eligible for premature release.
The counter said the state had written to the Centre in March 2016 itself seeking its concurrence for release of all seven convicts. "So far, no reply has been received from the government of India in this regard," it said
The Supreme Court had awarded death penalty to four of the 26 persons found guilty in the case, including Nalini and her husband Murugan. It awarded life to three others.
Nalini's sentence was commuted to life after Tamil Nadu government invoked Article 161 of the Constitution, which made the then Governor pass relevant orders in April 2000.
The death penalty of the three others, Murugan, Santhan and Perarivalan was commuted to life by the Supreme Court on February 18, 2014 on the ground of inordinate delay in disposing of their mercy petitions by the President.
Nalini filed a fresh petition seeking premature release stating that her representation on February 20 2014, should be considered as she had completed more than 20 years in jail.
She referred to a 2011 Government Order which facilitated the release of life convicts who served 20-year jail term.
Since the case was probed by a central agency, the state government is obliged to 'consult' the Centre in the case of premature release of convicts. The state government wrote to the Home Ministry on February 19, 2014 seeking its views on the proposal to release all seven life convicts.
The Centre had moved the Supreme Court to quash Tamil Nadu government's proposal.
The Supreme Court had in July 2014 restrained the state government from offering remission to life convicts. It was later modified a little.
On December 2, 2015, the Supreme Court ruled that the term 'consultation' in Sec 435(1) of CrPC implied 'concurrence'.
Only after that did the state government seek a clarification from the Centre, which is still awaiting reply.
The counter said the three-member bench of the Supreme Court had on April 18, 2016 decided to hear the Centre's case every Monday and Friday and added that the case had so far not been listed for hearing.
Tamil Nadu government detailed all correspondence between the state and the Centre in the counter.
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