A juveniles' court in New Delhi has deferred announcing the verdict of a teenager suspected of taking part with four others in the fatal gang-rape of a student on a moving bus, which triggered an outcry in India last year.

"The court has completed the hearing. The order has been deferred to July 25," public prosecutor Madhav Khurana said as he emerged from court on Thursday.

The juvenile, aged 17 at the time of the brutal assault in December, can be sent to a correctional facility for a maximum three-year term, which includes the time he has already spent in custody while waiting for the verdict.

The verdict is likely to cause further anger in a country attempting to turn a rising tide of violence against women and which has passed a new law toughening sentences for adults convicted of sex crimes.

The victim's family led calls for the teenager to be tried as an adult, alongside five men initially arrested over the savage crime on December 16, which led to weeks of protests in the capital and elsewhere.

The trial of four adult suspects continues but is expected to wrap up in the next few months, with the men facing a possible death sentence if convicted of rape and murder.

The fifth adult, alleged ringleader Ram Singh, died in jail in an apparent suicide.

A government panel set up after the Delhi gang-rape to recommend changes to sex crime laws rejected calls to lower the age at which people can be tried as adults from 18 to 16.