India's top court on Wednesday dismissed an appeal against the death penalty by one of four men convicted of gang-raping and murdering a woman on a bus in New Delhi, saying it found no reason to review the sentence.

Four men were convicted of the rape and murder of the 23-year-old woman who was tortured on a bus in New Delhi in 2012, an attack that triggered shockwaves across India and abroad.

The victim came from a lower-middle class family and worked in a call centre while she studied.

The incident exposed the scope of sexual violence against women in India prompting lawmakers to stiffen penalties in rape cases.

The victim, a physiotherapy student, was heading home with a male friend from a movie theatre when six men lured them onto a bus.

They assaulted the man with a metal bar, raped the woman and used the bar to cause massive internal injuries to her. 

The victims were dumped naked on the roadside and the woman died two weeks later.

Her mother told reporters she welcomed the ruling and hoped all four men would be executed soon.

"This is one step closer to justice," she said. - Reuters