A court in India has ordered police to protect the family of a woman allegedly gang-raped and killed by four high-caste men, as her brother said they feared reprisals over the accusations.

The 19-year-old woman was attacked in mid-September and died this week, sparking outrage and shining the spotlight again on sexual violence in India, particularly attacks against women of a lower caste.

With her home village in the northern state of Uttar Pradesh barricaded by hundreds of police, the victim's brother on Thursday told Indian television they were frightened.

"We're not safe in this village. They can do anything to us. We don't trust the police or the administration. Our fears have increased now," he said.

"We're on their radar more than ever before. They won't let us live. We might have to leave the village. We don't trust politicians."

The state's high court on Thursday ordered authorities to "ensure that no coercion, influence or pressure is exerted upon the family members of the deceased in any manner, by anyone."

It sharply criticised police for reportedly cremating the young woman in the middle of the night -- against the family's wishes and religious custom -- after her body was brought back from the New Delhi hospital where she died from her injuries on Tuesday.

"As it is, the deceased victim was treated with extreme brutality by the perpetrators of the crime, and what is alleged to have happened thereafter, if true, amounts to perpetuating the misery of the family and rubbing salt in their wounds," the judges said.

They set a hearing for October 12, summoning both police and the victim's family.

Students protest the alleged gang-rape of a  19-year-old woman in India's Uttar Pradesh state
Students protest the alleged gang-rape of a 19-year-old woman in India's Uttar Pradesh state AFP / Indranil MUKHERJEE

The late-night cremation further stoked accusations that local police were protecting the alleged culprits -- who have been arrested on charges of gang-rape and murder -- and their well-connected, high-caste families.

On Thursday the local police issued a statement saying that according to a forensic report "no rape was committed".

The findings, confirming those of a preliminary medical report and a postmortem, "exposed the conspiracy of those who tried to push the state into a caste turmoil", the statement quoted local police official Prashant Kumar as saying.

This contradicts statements from both the victim and her mother, and also findings from the Delhi hospital when she was admitted, media reports said.

Experts cast doubt on the forensic test cited by the police, saying it was conducted too long -- eight days -- after the attack.

Mishika Singh, a lawyer and activist, told AFP that the findings were "in no way conclusive proof to say rape was not committed".

"Ignoring the dying declaration of the victim on the basis of a non-conclusive forensic report goes to show the murky investigation being done by the police," Singh said.

The young woman's death comes months after four men were hanged for the 2012 gang-rape and murder of a student on a bus in New Delhi, in a case that came to symbolise India's problems with sexual violence.

The latest incident -- and another gang-rape and murder this week in the same area -- has sparked days of protests and candle-lit marches as well as condemnation from politicians, activists and Bollywood stars.

An average of 87 rapes were reported in India every day last year, according to data released Tuesday by the National Crime Records Bureau, but large numbers are thought to go unreported.