A Yazidi teenager who was sold to an Isis fighter has described how she was beaten and gang-raped on a daily basis in a harrowing account of her nine month ordeal.

The 17-year-old, who is now believed to be three months pregnant, was sold into sexual slavery at an 'auction' after militants overran the town of Sinjar, according to an aid worker who claims to have helped her after she fled from Isis.

Delal Sindy, who describes herself as a Kurdish activist, said the girl remembered her time being held captive by the group as “like choosing between death and death”.

Sindy said she was repeatedly gang-raped, whipped and had boiling water poured on her thigh in the months that followed. The Independent has been unable to verify this account.

The girl was moved from Iraq to the group’s stronghold in Raqqa, Syria, where she and other girls who were also sold into sexual slavery allegedly underwent invasive ‘tests’ to determine that they were still virgins.

“The day me and my sister were sold was the last day I saw my mother,” she was quoted as saying. “I will never forget when she started crying and pulling her hair when they took us.”

Iraq crisis: Yazidi nightmare on Mount Sinjar Show all 15 1 /15 Iraq crisis: Yazidi nightmare on Mount Sinjar Iraq crisis: Yazidi nightmare on Mount Sinjar Iraq crisis Displaced people from the minority Yazidi sect, fleeing violence from forces loyal to the Isis in Sinjar town, walk towards the Syrian border, on the outskirts of Sinjar mountain, near the Syrian border town of Elierbeh of Al-Hasakah Governorate Iraq crisis: Yazidi nightmare on Mount Sinjar Iraq crisis Displaced people from the minority Yazidi sect, fleeing violence from forces loyal to the Isis in Sinjar town, walk towards the Syrian border, on the outskirts of Sinjar mountain, near the Syrian border town of Elierbeh of Al-Hasakah Governorate Iraq crisis: Yazidi nightmare on Mount Sinjar Iraq crisis Displaced Iraqis from the Yazidi community settle at a camp at Derike, Syria. In the camps here, Iraqi refugees have new heroes: Syrian Kurdish fighters who battled militants to carve an escape route to tens of thousands trapped on a mountaintop Iraq crisis: Yazidi nightmare on Mount Sinjar Iraq crisis A pilot based at RAF Marham entering a Tornado GR4 prior to taking off for the reconnaissance mission over Iraq. Several RAF Tornado jets set off from RAF Marham in Norfolk this afternoon to travel to a "pre-position", from where they will fly to northern Iraq to provide improved surveillance of the situation on the ground. The jets, fitted with Litening III targeting and surveillance pods, will be able to fly over the crisis area to provide intelligence and help with the delivery of humanitarian aid Iraq crisis: Yazidi nightmare on Mount Sinjar Iraq crisis A British Royal Air Force (RAF) Tornado GR4 aircraft equipped with the Litening III pod from RAF Marham, eastern England, on their arrival at RAF Akrotiri Cyprus for their reconnaissance mission over Iraq Iraq crisis: Yazidi nightmare on Mount Sinjar Iraq crisis Aid inside a Royal Air Force (RAF) Hercules C130 J aircraft before being airdropped to civilians in Iraq Iraq crisis: Yazidi nightmare on Mount Sinjar Iraq crisis A Royal Air Force (RAF) Hercules C130 J military transport plane at RAF Akrotiri in Cyprus. Britain made a third round of airdrops of supplies to aid refugees stranded on a mountain in northern Iraq, officials said, as Tornado fighters arrived at an RAF base in Cyprus preparing to provide surveillance support for the humanitarian effort Iraq crisis: Yazidi nightmare on Mount Sinjar Iraq crisis Royal Air Force (RAF) Tornado GR4 aircraft, flown in from Britain, stand on the tarmac at RAF Akrotiri in Cyprus Iraq crisis: Yazidi nightmare on Mount Sinjar Iraq crisis A displaced man helps a woman, both from the minority Yazidi sect fleeing violence from forces loyal to the Isis in Sinjar town, as they make their way towards the Syrian border, on the outskirts of Sinjar mountain, near the Syrian border town of Elierbeh of Al-Hasakah Governorate Iraq crisis: Yazidi nightmare on Mount Sinjar Iraq crisis Iraqis including Turkmen, Shabaks, Kurds, Yezidis and Christians, fleeing from assaults of army groups led by Isis, take shelter at Bahirka Camp in Arbil Iraq crisis: Yazidi nightmare on Mount Sinjar Iraq crisis Displaced Iraqis from the Yazidi community look for clothes to wear among items provided by a charity organization at the Nowruz camp in Derike, Syria Iraq crisis: Yazidi nightmare on Mount Sinjar Iraq crisis Displaced Iraqis from the Yazidi community gather for food at the Nowruz camp in Derike, Syria Iraq crisis: Yazidi nightmare on Mount Sinjar Iraq crisis Displaced Iraqis from the Yazidi community gather for food at the Nowruz camp in Derike, Syria Iraq crisis: Yazidi nightmare on Mount Sinjar Iraq crisis Syrian Kurdish Peshmerga fighters take a sick Iraqi Yazidi woman to the clinic at Nowruz camp in Derike, Syria Iraq crisis: Yazidi nightmare on Mount Sinjar Iraq crisis Sick displaced Iraqis from the Yazidi community wait for treatment at a clinic at Nowruz camp in Derike, Syria

The teenager said the Chechen militant, who called himself Al-Russiyah, and his team of bodyguards would force her to recite passages of the Koran while assaulting her.

“He beat me and would be with at least one other man every time he had sex with me,” she said.

Al-Russiyah also took two other girls at the same auction, where her 10-year-old sister was sold to a "high-profile" fighter. She said Al-Russiyah would strip all of them naked and choose a girl each morning. After he had made his choice, his bodyguards would also choose a girl to sexually assault.

The girl finally managed to escape when Al-Russiyah and his bodyguards were killed by Peshmerga forces near Sinjar, but her ordeal is far from over.

"My father is dead, I have no idea where my mother and sister are," she told Sindy. "What have I to live for? I try to forget everything, but even when I close my eyes I see them in front of me. I want to kill myself."

A recent report by Human Rights Watch found Isis fighters are committing widespread, organised and systematic rape and sexual assault on Yazidi women and girls in what may amount to a crime against humanity.