Five senior police officers have been suspended over their handling of an investigation into the gang-rape and murder of a 19-year-old woman that has sparked outrage across India and triggered days of protests.

The seriously injured teenager from the disadvantaged Dalit caste was found in mid-September outside her village in northern India's Uttar Pradesh state and died this week in a New Delhi hospital.

The police have arrested four high-caste men on charges of gang-rape and murder.

But the police have faced criticism for cremating the woman's body in the middle of the night -- reportedly with the help of some petrol -- against the wishes of her family and religious custom.

A senior policeman on Thursday sparked further outrage after claiming that a forensic report and an autopsy had shown that the woman had not been raped.

This contradicts statements from the victim and her mother and reported hospital findings, while experts said the forensic test was carried out too long after the attack.

Hundreds of police have also barricaded the village, preventing the woman's family from leaving and journalists and opposition politicians from talking to them.

The family's mobile phones have also reportedly been seized.

The gang-rape and murder of a 19-year-old woman has triggered protests across India
The gang-rape and murder of a 19-year-old woman has triggered protests across India AFP / Money SHARMA

The victim's brother told one Indian news channel that the family were scared for their lives. The local high court has ordered authorities to provide the family protection.

Uttar Pradesh chief minister Yogi Adityanath late Friday announced the suspension of the Hathras district police chief and four others.

The Hindu monk and close ally of Prime Minister Narendra Modi also announced that the victim's family, the accused and the suspended policemen would all undergo lie-detector and drug tests.

On Friday evening in the latest protest, around 500 people including the capital's chief minister and a prominent Dalit politician gathered in central New Delhi demanding justice.

"We (women) are not actually free, even though India is independent," Sanskriti, one of the women at the Delhi protest site told AFP.

"This is something I want to raise my voice against. And I just wish all the people get united and they understand that it is high time to do something about it," she added.

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 epidemic of sexual violence.

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