Former Indian prime minister and Congress party leader Rajiv Gandhi addresses an election campaign meeting in Kishan Gunj, Bihar in 1991. File picture: K.M. Kishan/Reuters

New Delhi - A life convict in the assassination case of former prime minister Rajiv Gandhi walked out of a southern Indian jail on Thursday on a month's parole for her daughter's wedding.

"Nalini Sriharan has been released on parole. It comes with several conditions," said an official at the Special Prison for Women in Vellore town in Tamil Nadu state.

Rajiv Gandhi was killed in a suicide bombing by Sri Lanka's rebel Liberation Tigers of Tamil Eelam in May 1991 in Sriperumpudur in Tamil Nadu.

Indian security agencies that unravelled the plot found Sriharan, now 52, was part of the assassination squad.

Sriharan, an Indian national, was initially sentenced to death, but this was commuted to life imprisonment after she gave birth to her daughter in jail. Her husband Murugan, a Sri Lankan, is also serving a life sentence.

The Madras High Court on July 5 granted Sriharan 30 days' parole to make arrangements for her daughter's wedding.

The court has asked Sriharan not to talk to politicians or the media, NDTV news channel reported. She has to remain within Vellore district at a known location with a police escort.

Television channels showed Sriharan walking out of the women's prison in Vellore town in Tamil Nadu wearing an orange and red silk sari escorted by policewomen.

She was received by her mother, a retired nurse, NDTV reported. Sriharan's daughter who is a medical student in Britain is expected to join them next week.

The only other time Sriharan has left prison was for a day in 2016 to attend her father's funeral.