"DCW filing Special Leave Petition in SC tonight. Will go to Judge's house, will try get hearing tonight against Nirbhaya convict's release," Swati Maliwal, the body's chief, tweeted.
The convict is scheduled to be released tomorrow.
The development comes on a day the victim's parents were detained and later released after they held a protest against allowing the juvenile convict to walk free.
The convict, who is now 20 years old, has been taken to an undisclosed location from a correction home in North Delhi amid concerns that there was threat to his life.