Police Sub Inspector H S Kamraj of Mumbra police station told PTI that the victim was brought to the house of accused Zakil Ahmed Shaikh, her paternal uncle, as his wife was not keeping well and she would help her in household work.
The incident took place in February when Zakil's wife had gone to the hospital and his brother-in-law Shanu Rais Beigh sexually assaulted the girl, the complaint filed by her said.
According to the victim Rias abused her three times last month, promising to marry her but later backed out and threatened to kill her parents if she did not fulfil his demands.
No arrests have been made in the case, police said.