The incident took place this morning when the boy was playing outside his residence in Sikandarpur town. His 20-year-old cousin, Javed, took him to a secluded place and sodomised the minor, Superintendent of Police, KC Goswami said.
The matter came to light when the minor narrated the incident to his parents who later registered an FIR, Goswami added.
Javed was apprehended today by the police following the FIR, he said, adding that further investigation is on in the matter.