Lt Gen Singh has been appointed on deputation basis for two years or till his superannuation from Army or until further orders, a Home Ministry spokesperson said.
The post of DG of Assam Rifles has been lying vacant since February after Lt Gen Rameshwar Roy was repatriated to the army by the Home Ministry, months after allegations of fund misuse cropped up against him.
Lt Gen Singh was commissioned in 1975 in the Bihar Regiment and in his career spanning over 37 years has a coveted career profile both in command and in staff appointments.
The Shillong headquartered Assam Rifles, which guards the 1,648-km-long Indo-Myanmar border and fights insurgency in the Northeast, is administratively under the Home Ministry while its operational control lies with the Defence Ministry.
After Lt Gen Roy's departure, second-in-command Maj Gen R K Lakhanpal is officiating as the Director General of the country's oldest paramilitary force.
Following an inquiry into the allegations of misuse of regimental funds, the Home Ministry had found nothing against Lt Gen Roy and concluded that the complaint was baseless and mala fide.