The Supreme Court on Friday upheld the death sentences of all four convicts in the fatal 2012 gang rape of Nirbhaya in a moving bus here, a "rarest of rare" crime that sparked nationwide outrage over violence against women in the country.

"If ever a case called for hanging, this was it," said a bench of Justice Dipak Misra, Justice Ashok Bhushan and Justice R. Banumathi. This sparked off loud clapping in the packed courtroom by relatives of the victim -- whose identity is protected by law -- and others. 

The judges said the aggravating circumstances against Mukesh Singh, Pawan Gupta, Vinay Sharma and Akshay Thakur - all in their 20s - far outweighed the mitigating circumstances, such as their poor family background, age, good conduct in prison and their children cited in their favour.

"If the dreadfulness displayed by the accused in committing the gang-rape, unnatural sex, insertion of iron rod in the private parts of the victim doesn't fall in the rarest of rare category, then one may wonder what else would," Justice Banumathi said, declining the convicts' appeal.

Describing it as a crime of "mental perversion and extreme brutality" where in intestines of the victim were "perforated in the most savage and inhuman manner", Justice Misra said: "It sounds like a story from a different world humanity has been treated with irreverence."

Justice Misra, also speaking for Justice Bhushan, said the convicts "don't deserve leniency" in view of their "brutal, barbaric and diabolical" conduct and "their brutish behaviour" with the victim.

The four were convicted for raping and assaulting the 23-year-old paramedical student inside a moving bus on December 16, 2012. The rapists, six in all, pounced on the young woman who had boarded the bus with her boyfriend to go home after seeing a movie "Life of Pi". 

As the bus moved on south Delhi roads, the convicts pulled out her internal organs with a rusted L-shaped iron rod used with a wheel jack. This led to her death due to internal injuries 13 days later in a Singapore hospital. 

After committing the crime, they dumped the woman and her friend on the side of a road. Some onlookers alerted the police. The sheer brutality of the crime led to nationwide revulsion -- and street protests.

A fifth accused, Ram Singh, committed suicide in the Tihar Central Jail here. The sixth, a juvenile, who was accused of ripping apart the woman's intestines, was sent to a correction home and has been released after serving his probation period.

Taking note of the serious injuries and the severe nature of the offence, the judges said they were upholding the death sentence first pronounced by a lower court and upheld by the Delhi High Court.

Nirbhaya's mother was in tears as she heard the judges pronouncing death to the rapists. "I am very satisfied. I am happy today."

The victim's grieving father hailed the the Supreme Court that "heard our voice and understood the suffering Nirbhaya underwent". 

"It has given justice to Nirbhaya and the entire country," he said, referring to his daughter by the name -- which means fearless -- given by the media.

The convicts' lawyer, A.P. Singh, pledged to file a review petition. "I am not satisfied with the judgement," he said. "It is a violation of human rights. Someone cannot be hanged just because of public sentiments."

The last recourse for the convicts will be to file a mercy petition and seek clemency from President Pranab Mukherjee. 

Women and Child Development Minister Maneka Gandhi said she was happy. "I wish it had come sooner. It was a horrible experience and suffering for the family."

The Delhi Commission for Women welcomed the capital punishment. "Finally, justice was delayed but not denied," said its chief, Swati Maliwal.