The following information has been extracted from a book titled 'Inside RAW, the story of India's secret service' written by Asoka Raina. He clearly acknowledged that RAW had helped Shanti Bahini to carryout insurgency in Chittagong Hill Tracts.
"The East Pakistan government had built a dam over the river Kaptai. The Chakma Tribals had been moved out with the assurance that they would be resettled. But the resettlement never took place. Instead, towards the end of the 70s, Bengali Muslims moved into the Chittagong Hill Tracts and began buying out the poor Chakma Tribals. Religious persecution followed soon after. For a while, they were assisted after the formation of Bangladesh. But with the change of government after the coup in Bangladesh, the old persecution followed. They moved towards India for help. Like the Mukti Bahini, they had continued to nurture their old RAW contacts. They sought them again.
Having crossed across Agartala, they began negotiating. Their demands for protection of their families and children, if and when they were forced to move to India, was accepted by the government. They were adamant in fighting their own battles. They wanted protection in a corridor through which their families could enter India. The Mizo threat had persisted...................the Chakmas offered to lose themselves in the Chittagong Hill Tracts and infiltrate among the Mizo rebels, and pass on information to the Indian government, in lieu of the guarantee of asylum to their families. This offer was accepted."