The incident took place in Mishrikh area of Sitapur district.
Sources said the girl had gone to relieve herself in the fields in Benipur Majra Sarsai but never returned. Her body was later spotted hanging from a tree a few hundred metres from her house.
The father of the victim has lodged a complaint with the police saying that Ramesh from the same village often harassed her and had threatened the victim when she said she would inform her family about it.
The police said a complaint has been received and they were probing the matter. A medical examination will also be conducted to confirm rape.
The shocking incident comes barely a week after the gruesome gang rape and killing of two minor sisters in Budaun that led to a national outcry. A CBI probe has been ordered in the Budaun case.