Acting on a tip-off, the police dug out the weapons hidden inside a ditch at a cremation ground in remote Sadiya town bordering Arunachal Pradesh.
The weapons recovered include 16 US-made M-16 rifles, two rocket launchers and huge quantities of magazines of .303 rifle.
The arms were suspected to have been hidden by four Maoist cadre, who were later killed in an encounter with the police in May this year.