The 18-year-old, who was 17 when he was one of six who viciously gang-raped and murdered a 23-year-old woman in South Delhi, was sentenced on Saturday to three years in a juvenile remand centre, the maximum penalty allowable under the law.

The punishment is grossly inadequate, the victim's parents and some politicians have said, demanding the juvenile be executed.

“It is a crime to be born a girl in this country. Is this justice?,” her father said. “We have lost our daughter in such a brutal manner… but the court finds it fit to allow him to lead a complete life after a few months in a correction home.”

The victim's mother said the juvenile should face the death penalty, as his adult co-accused might in coming months.

“The only thought that has kept me sane till now was that of seeing my daughter's attackers hanged. This is no punishment.”

Senior leader with the opposition Bharatiya Janata Party, Sushma Swaraj, said she would move a private member's bill to allow for harsher punishments of juveniles.

“This meagre punishment does not do justice… the sentence must be commensurate with the nature and gravity of the offence.”

But others have appealed for calm, and said the rule of law must prevail.

“People are demanding the gallows for him, but I appreciate the decision as the juvenile should be given a chance to turn into a good human being,” general secretary of the People's Union for Civil Liberties Kavita Srivastava said.

“There should be every effort at the rehabilitation and the eventual reintegration of the child as a constructive member of society,” said Meenakashi Ganguly, South Asia Director of Human Rights Watch.

The juvenile was said to be the most violent during the hour-long attack, the savageness of which shocked a country in which sexual violence against women is common.

Just before 10pm on Sunday December 16, the victim and her fiancé boarded a bus in south Delhi. The five men and the juvenile on board locked the doors and beat the woman's fiancé unconscious with an iron bar before taking turns in repeatedly raping and bashing her.

They raped her with the iron bar, causing massive internal injuries, before throwing her unconscious body, along with that of her partner, from the moving vehicle onto the road.

She died 13 days later in a Singapore hospital.

The juvenile is the first offender sentenced. The alleged ringleader, Ram Singh, was found hanged in his prison cell, reportedly an act of suicide, in March.

The other four attackers, aged between 19 and 28, are awaiting sentence.

The especial brutality of the attack sparked widespread outrage across India – particularly amongst the country's urban middle-class – and brought hundreds of thousands to the streets in protest.

But, eight months on, reports of gangrapes and violent assaults are still common. The culture of violence against women seems unaffected by the publicity of this trial.

On the same day as the juvenile was sentenced, four men, including two policemen, were arrested for gang-raping a 28-year-old woman in Noida, on the outskirts of Delhi.

In Mumbai, just over a week ago, a 23-year-old photojournalist was gangraped by five men when she was on assignment in Parel in the city's south.

And in Jind, in Haryana, a 20-year-old dalit girl was allegedly raped and murdered a week ago, and her body dumped next to a canal. Authorities say there is no evidence of rape, but her family say police are trying to keep the case quiet, and have refused to search for her attackers because the victim was low-caste.