The youngster could not speak, behaved like an animal and ran on all fours. She ate food from the floor without using her hands, said doctors treating her.
The girl, believed to be aged between 10 and 12, was naked and looked very comfortable roaming with the primates when she was discovered by tree surgeons in the Katarniya Ghat forest range.
When they tried to rescue her, they were chased away by the monkeys before a policeman was later able to take her away despite being attacked himself by the animals.
He drove his patrol car at speed while the monkeys ran after the vehicle.
Police officer Dinesh Tripathi said: “When he called the girl, the monkeys attacked him but he was able to rescue the girl. He sped away with her in his police car while the monkeys gave chase.”
Dr D K Singh from Bahraich district hospital, said: “She was rescued and brought here. When she arrived here, her hair was dishevelled and she was not wearing any clothes.
“She was very thin and weak, and it seemed like she had not eaten for many days.
“Her behaviour was totally like an animal. The way she moved, even her eating habits were like that of an animal.
“She would throw food on the ground and eat it directly with her mouth, without lifting it with her hands. She used to move around using only her elbows and her knees.”
Doctors in Uttar Pradesh state have been treating her since she was discovered in January.
She has now started walking normally and eating with her hands.
She is still unable to talk, but understands whatever people tell her and also smiles, said a hospital spokesman.
Her story has similarities with Rudyard Kipling’s tale about a boy called Mowgli who was brought up by wolves.
Police are reviewing reports of missing children to try to identify the girl.
Officers are also attempting to find out how she got into the forest and who her parents are.
She will be sent to a home for juveniles until she is identified.
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