A 23-year-old rape victim set on fire by a gang of men, which included her alleged rapist, has died in a New Delhi hospital, the doctor treating her said on Saturday.

The woman was on her way to board a train in Unnao district of northern Uttar Pradesh state to attend a court hearing over her rape when she was doused with kerosene and set on fire on Thursday, according to police.

The attack, the second major case of violence against women in the past two weeks, has sparked public outrage in India.

The woman died on Friday after suffering a cardiac arrest, Dr. Shalabh Kumar, the head of burns and plastic department at New Delhi's Safdarjung Hospital told Reuters.

"She was having 95 per cent burns," he said, adding the woman's wind pipe was burnt and "toxic and hot fumes" had filled her lungs.

The woman had filed a complaint with Unnao police in March alleging that she had been raped at gun-point on December 12, 2018, police documents showed.

Having been subsequently jailed, the alleged rapist was released last week after securing bail, police officer S.K. Bhagat said in Lucknow.

Uttar Pradesh is India's most populous state and has become notorious for its poor record regarding crimes against women, with more than 4,200 cases of rape reported there in 2017 — the highest in the country.

On Friday, Indian police shot dead four men who were suspected of raping and killing a 27-year-old veterinarian near Hyderabad city, drawing applause from across the country angry over violence against women.

But many were also concerned that police had over reached in shooting the alleged suspects without any trial.