According to an NIA statement, the workers were involved in "hatching conspiracy" and raising funds by terrorising local people and bodies such as schools, panchayats, government officials and owners of petrol pumps.
The chargesheet has been filed under various sections of the Unlawful Activities (Prevention) Act, 1967.
Among the arrested is KCP's self-styled commander-in-chief Laishram Ranjit Singh Meitei.
The three were arrested in October last year. (ANI)