Nusrat told police she'd been assaulted by her headmaster. Days later, she was dead.

With AAP.

When Nusrat Jahan Rafi approached police claiming she had been sexually harassed by her Islamic school’s principal, the officer pressed record on his mobile phone. The footage shows the 18-year-old Bangladeshi girl visibly distressed, attempting to cover her face with her hands, as she detailed how Siraj-Ud-Daula summoned her into his office and repeatedly touched her in an inappropriate manner.

The officer’s response? It’s “not a big deal”. “Move your hands from the face, stop crying, nothing happened that you have to cry.”

That footage, taken without the teenager’s consent, was posted to social media by the officer. Less than two weeks later, Nusrat Jahan Rafi was dead.

According to local police, the teenager had been lured onto the roof of a cyclone shelter at her school in the rural town of Feni on April 6, where she was set upon by a group of people, three of whom had their faces concealed by burqas.

Nusrat said the attackers asked her to withdraw the charges against the headmaster, and that when she refused, her hands were tied and she was doused in kerosene and set alight. Nusrat told the story to her brother in an ambulance on the way to the hospital and he recorded her testimony on his mobile phone.

“The teacher touched me,” she says in the video, according to BBC. “I will fight this crime till my last breath.”

She died four days later in hospital, with burns covering 80 per cent of her body.

Nusrat's murder has sparked widespread protests across Bangladesh, as women's rights advocates highlight the stigma that plagues those who report sexual harassment and assault in the conservative Muslim-majority nation. Among their pleas, that the Government repeal a law which states that “when a man is prosecuted for rape or an attempt to ravish, it may be shown that the prosecutrix was of generally immoral character".

"We want justice. Our girls must grow up safely and with dignity," Alisha Pradhan, a model and actress, told The Associated Press during a demonstration on Friday. "We protest any forms of violence against women, and authorities must ensure justice."

In a statement, Human Rights Watch's South Asia Director, Meenakshi Ganguly, said: “The horrifying murder of a brave woman who sought justice shows how badly the Bangladesh government has failed victims of sexual assault. Nusrat Jahan Rafi’s death highlights the need for the Bangladesh government to take survivors of sexual assault seriously and ensure that they can safely seek a legal remedy and be protected from retaliation.”

Tens of thousands of people attended Nusrat's funeral prayers in Feni to show support for her family and the cause.

Arrests made over fatal attack on Nusrat Jahan Rafi.

At least 17 people, including students, have been arrested in connection with the case so far, said Banaj Kumar Majumder, the head of the Police Bureau of Investigation.

Police said the suspects told them during interrogations that the attack on Nusrat was planned and ordered by the principal from prison when his supporters visited him. It was timed for daytime so that it would look like a suicide attempt, Majumder said.

As investigations continue, the policeman who filmed Nusrat's sexual harassment complaint has been removed from his post and transferred to another department.

While Nusrat's case is now being treated with urgency, that wasn't so prior to her death. According to Human Rights Watch, her family, who agreed to help her file the original complaint against the headmaster, received multiple death threats after he was taken into custody.

Prior to the attack on Nusrat, local students, two of whom are among those arrested, organised protests calling for Siraj-Ud-Daula's release. Several influential local politicians were seen attending the event.

Bangladheshi Prime Minister Sheikh Hasina promised Nusrat's family when they met in Dhaka that those responsible would be punished.

"Nusrat’s killers won’t be spared," she told media last week. "I personally believe they would have to face exemplary punishment so that none can dare to commit such heinous crimes in future."