Lalzirliana said some militants active in the Mizoram-Manipur-Assam border areas were sending letters demanding money from government employees posted in those areas.
He appealed to government employees not to succumb to the pressures from "unwanted elements" and warned that those indulging in the illegal activity would be punished.
Meanwhile, Manipur-based Hmar People's Convention (Democrats) has said the outfit was not involved in the extortion racket in the border areas.
A statement issued by the Hmar group said the extortionists were using its name to tarnish the image of the outfit.
HPC(D) has never harassed government employees working for the development of the Hmar people, the statement claimed, adding that "the criminals belonged to another group, but is using the name of HPC(D)."