Thangdeihpianga (38) of Champhai was arrested while carrying the arms concealed in a plastic sack in a two-wheeler bearing no registration number.
The accused claimed that he had an accomplice who was a Myanmarese national and the arms were brought from Myanmar through the porous border near Ngur hamlet via the border river Tiau.
While the police were yet to ascertain the destination of the weapons, state intelligence officials did not rule out the possibility of Bangladesh rebels belonging to the Chakma community being involved in the smuggling.