Tamil Nadu Chief Minister J Jayalalithaa announced in the assembly her government's decision to set free all the seven convicts.
DMK chief M Karunanidhi has welcomed the Tamil Nadu government's decision to release Rajiv Gandhi's killers.
The DMK President said, "The Centre should immediately approve Tamil Nadu government's decision to release Rajiv killers. I'm hopeful they would, I will be happy then. It's not a prompt decision by the state government. They ridiculed me when I proposed it, but I appreciate the Tamil Nadu government for the decision."
However, Mr Karunanidhi said the decision could have been taken in 2011 itself.
On compensation for the convicts for the delayed decision, he said, "Nobody has spoken to us about that. We have not thought about that. If there is such a demand then it is for the government to decide."
Tamil Nadu Chief Minister J Jayalalithaa announced in the assembly her government's decision to set free all the seven convicts - V Sriharan alias Murugan, AG Perarivalan alias Arivu, T Suthendraraja alias Santhan, Nalini, Robert Payas, Jayakumar and Ravichandran.
The decision was taken in the Cabinet meeting on Wednesday.
Ms Jayalalithaa said the state government's decision would be sent to the Centre. If it does not respond within three days, the state government would release all the seven convicts.
Former prime minister Rajiv Gandhi was killed in May 1991. The conspirators were convicted by a TADA (Terrorist And Disruptive Activities (Prevention) Act) court in January 1998 and were awarded death sentence, which was confirmed by the apex court on May 11, 1999.