Nalini, serving life term in the Rajiv Gandhi assassination case, has been shifted from Vellore prison to Puzhal jail in the suburbs of Chennai after she complained of harassment by jail officials.
Official sources said 44-year-old Nalini was transferred from high security Vellore prison to Puzhal amid tight security.
Nalini had earlier this month complained of harassment by jail officials. She had later alleged her life was under threat and she was assaulted by prison authorities.
In letters to the ADGP Prisons, Dr K R Shyamsundar, she had also alleged that attempts were being made to poison her food.
After she levelled the allegations, the Tamil Nadu Government had appointed a committee headed by a top prison official to look into them.
The state government had earlier this year rejected the plea of Nalini and three other convicts in the Rajiv Gandhi assassination case for premature release, based on a report by the prison advisory board. Later, her plea for release under general amnesty was also turned down by the Madras High Court.
Nalini was sentenced to death by a special court along with 25 others in January 1998. The Supreme Court had confirmed the capital punishment.
However, her death penalty was commuted to life by the state government on April 24, 2000 allowing a clemency petition. Congress President Sonia Gandhi had favoured reduction of her punishment considering the plight of Nalini's young daughter.