NEW DELHI: Indian newspapers and politicians called for harsher punishments for juveniles Sunday after the first verdict in the New Delhi gang-rape case saw a teenager sentenced to three years' detention.

The rape and murder of a 23-year-old student by six people, including a 17-year-old on a moving bus last December sparked nationwide protests and led to calls for longer sentences in sexual assault cases.

“TRAVESTY: December 16 teen rapist 'gets away' with murder,” a headline in the tabloid Mail Today read, summing up the mood.

The convicted teen will now spend about 28 months in a juvenile detention centre, having already spent about eight months in custody while awaiting a verdict.

“He can watch TV, play games while doing time,” the Hindustan Times reported, while pointing out that police sources had earlier described the teenager as “the most brutal” among the six attackers.

The Times of India said the gang-rape victim had “been denied justice” by the juvenile court.

“Almost everybody will agree that there is something wrong with a system that allows someone who has raped and brutalised a girl, resulting in her death, to walk free after just three years because he was a 'juvenile',” it said in a front-page editorial.

It is time for India to change the law and measure “the age below which a person is considered juvenile to the nature of the crime”, it said.

Sushma Swaraj, leader of the opposition in the lower house of parliament, said on Twitter that she was set to introduce a bill on Friday, calling for amendments to juvenile laws.

“This meagre punishment of just three years does not do justice,” Swaraj tweeted.

“The sentence must commensurate with the gravity of the offence irrespective of the age of the offender,” she added.

The rape victim's family said they would continue to fight for a tougher punishment.

A petition in the Supreme Court has been filed by politician Subramanian Swamy challenging the law and requesting that the gravity of the crime be taken into account during sentencing.

The victim, a physiotherapy student, died of internal injuries two weeks after being raped and assaulted with an iron bar on the night of December 16.

Her male companion was also beaten up before both were thrown bleeding from the bus.

A separate trial of the four adult suspects in a fast-track court is hearing closing arguments and is expected to wrap up in the next few weeks, with the men facing a possible death sentence if convicted.

The fifth adult, the suspected ring leader, died in jail in an apparent suicide.