The shocking incident took place two days ago at a private clinic in Nawada town where the girl, Anchal Kumari, was admitted a month ago with a fracture and a swelling on her left hand, the FIR alleged.
The doctor, Dr Arvind Kumar, amputated the left hand of the minor girl after he failed to treat the swelling, according to the FIR.
The matter came to light today after the girl's kins and other villagers protested before the district collectorate demanding stringent action against the medico.
Taking a serious view of the matter, district SP Parvez Akhtar said that a medical board had been set up to probe the incident, which would submit its report at the earliest on the basis of which necessary action will be taken against the doctor.
Meanwhile, district civil surgeon Madheshwar Prasad Sharma has agreed to the charge of negligence by the doctor in the treatment of the girl.