NEW DELHI: The youngest of six men convicted of the 2012 gang rape of a woman, in a case that shocked India, moved closer to being freed on Sunday, after a court said it could not extend his three-year sentence.

The case turned a global spotlight on the treatment of women in India, where police say a rape is reported every 20 minutes, and the sentence for the young man sparked debate over whether the country is too soft on youthful offenders.

The court was hearing a petition by a ruling-party politician demanding a longer sentence for the man, who was 17 at the time of the crime, after he had received the maximum punishment of three years from the Juvenile Justice Board.

The Delhi high court judges said they could not halt the man's release because his sentence complied with existing law.

"We don't want to interfere in the Juvenile Justice Board," the two judges said in their ruling on Friday.

A lawyer for the man declined to comment.

In 2012, the man and five adult companions lured the 23-year-old trainee physiotherapist and her male friend onto a bus in the Indian capital, where they repeatedly raped the woman and beat both with a metal bar before dumping them on to a road.

The woman died two weeks later of her injuries.

Four of the adults were sentenced to death while the fifth hanged himself in prison. The death sentences have not yet been carried out.

Police accused the teenager of being violent, and said he pulled out part of the woman's intestines with his hands.

"We want every woman to protest on the streets of the country to stop his release," Asha Devi, the victim's mother, told Reuters.

"There is no way that society can allow a dangerous man to walk free."

India responded to the public outcry over the rape by fast-tracking tougher laws against sex crimes, and members of the government of Indian Prime Minister Narendra Modi have pushed to change the juvenile law and reduce the age of attaining adulthood to 16, from 18.

The petition was filed by Subramanian Swamy, a politician in Modi's Hindu nationalist party, who called for the law to be reinterpreted.

The final call on the man's release would be made by a management panel of the Juvenile Justice Board after assessing if he had been "socially mainstreamed", Swamy told Reuters.