NEW DELHI (Thomson Reuters Foundation) - Seven years after the gang rape of a student on a Delhi bus sparked global outrage, her mother on Wednesday demanded justice for a new rape victim, whose murder has triggered mass protests over women's place in modern India.

"When will things change?" asked Asha Singh, the mother of the 23-year-old woman whose death in 2012 shocked the world and led to tougher laws against sexual abuse in India.

"Nothing has changed - despite everything."

She spoke to the Thomson Reuters Foundation a week after a 27-year-old vet was raped, suffocated and her dead body set alight on the outskirts of the southern city of Hyderabad, according to police.

Four men have been arrested in connection with the crime.

But nationwide outcry over her death - demonstrators have taken to the streets in their thousands - will change nothing absent concrete action from the top, Singh said.

"Until strict steps are taken by the government and until laws are actually implemented, nothing will come of our screaming, protesting and candle marches. We need speedy justice now," she said in a phone interview.

She spoke as police said they had discovered the charred bodies of two more women in eastern Bihar state within 24 hours.

GRIM RECORD

India has a grim record of sexual violence against women, with an average of some 90 rapes reported each day in 2017, according to latest federal data.

A Thomson Reuters Foundation poll of gender experts in 2018 rated India as the world's most dangerous country for women.

Outrage over the vet's murder - her charred body was found on scrubland under a flyover - is running high, with protesters and lawmakers demanding tough and quick punishments, including public lynchings.

The mother of the vet, who cannot be named for legal reasons, told local media she wanted her daughter's attackers to be burnt alive.

"I can completely understand what her parents are going through. I want them to know that they are not alone," said Singh, who lives in Delhi.

"We may be far by distance but we are together in our fight for justice."

WHAT NEXT?

Just as her daughter's rape shone a light on women's place in Indian society, the current case has provoked outrage on social media with #HangRapists trending on Twitter in India.

But Singh said that was not enough.

She urged India to fix its notoriously slow and creaking criminal justice system, noting her daughter's attackers were still alive despite being sentenced to death.

Cases take at least six years on average to final ruling, according to governance tracking group Daksh.

As in the 2012 gang rape, a special fast-track court will hold the trial for the latest case.

"I have been fighting for my daughter's justice for seven years now, but I hope this family does not have to wait as long," she said.

"Our law and order - from the police to the courts - have to function effectively, transparently and quickly. Only then can we hope for any change. Otherwise, everything just remains on paper."

India's National Commission for Women has condemned the attack and vowed it "won't leave any stone unturned till these perpetrators get the punishment they deserve".

The commission advises government but has no powers.

On Monday, India's defence minister condemned the attack and told parliament the government was "open to every suggestion to curb such heinous crimes".