The cartridges were traced when Phuntso Dorjee kept his bag in X-ray machine during security check at around 4.50 AM, a senior police official said.
Dorjee, a resident of Bomdila Urban C of Arunachal Pradesh's West Kameng district, was to board a SpiceJet flight (SG-885) to Bagdogra from here.
It was during security clearance when the 12 live rounds of 0.32 calibre were recovered from his hand bag, the official said.
He was taken into custody by the CISF personnel and later handed over to police for necessary action.
During interrogation, Dorjee produced his arms licence with a validity till 31 December 2013, but it was valid in Arunachal Pradesh and Assam only.
