Amitabh Kumar Das, posted as superintendent of police in the commission, had Monday sent a report to Inspector General (Special Branch) Jitendra Gangwar, alleging Singh's links with the caste outfit.
Das had also requested Gangwar to inform the Intelligence Bureau about his report.
"Commission has issued notice to Das and asked him that on what authority he had sent a report to IG, Special Branch," BHRC chairman Bilal Nazki said here.
Das has been directed to submit his explanation within a week.
In 2003, Das, then superintendent of police of Arwal district, had demanded that the Ranvir Sena be declared a terrorist group.
His demand had come while appearing before a commission probing the alleged links of senior politicians including a union minister from Bihar with the Ranvir Sena.