HNLC publicity secretary Sainkupar Nongtraw has confirmed Kharmawphlang's joining the outfit.
The announcement was made by Kharmawphlang last night and his resignation letter was sent to KSU president Daniel Khyriem and its general secretary Auguster Jyrwa.
"I have taken this step personally with a motive to send a strong message to the state government that there is a need to protect our indigenous people," Kharmawphlang said in his resignation letter.
The move has come as a boost to HNLC, which had lost ground due to its extortion and anti-people move in the last decade.
The chairman of the outfit Julius K. Dorphang had come overground in 2007 and is currently an Independent legislator representing Mawhati constituency in Ri Bhoi district.