Dibrugarh District Superintendent of Police Rana Bhuyan said the ULFA(I) cadre has been identified as Raktim Moran (22), a resident of Mudai Gaon in the district. He was a "lance corporal".
Bhuyan said Moran has deposited one AK-81 rifle, one Chinese grenade, three magazines and 79 rounds of ammunition.
Having joined the banned terrorist group in 2011, Moran had undergone training in Myanmar.
Bhuyan said he had been sent around a month back to carry out sabotage work in Upper Assam.
While surrendering his arms, Moran told PTI that currently four training camps of the ULFA (I) are operating inside Myanmar with around 250 cadres, apart from some NSCN(K) militants.
"There is another transit camp in Nagaland along the international border. Around 50 ULFA cadres are present there also," he claimed.