They were all booked under Unlawful Activities Prevention (UAP) Act for their anti-social activities, a senior police officer said.
Acting on a tip off, Special Operation Team (SOT) commandos of the police raided the spot and arrested Manbhalang Jyrwa alias Man from Nongrim Hills area in the city last night.
According to the police, Man, whose original name was Sulfiyan Ali Hazarika, is a close confidant of the outfit's publicity secretary Sainkupar Nongtraw and was responsible for editing and publishing articles and propaganda of the outfit.
"The arrested cadre is behind the several 'Face book pages' depicting the resurgence of the outfit like 'We are Back' and the claiming of responsibility for the firing by the HNLC cadres at Lumdiengjri Police Station last year," Superintendent of Police East Khasi Hills M Kharkrang said.
From his possession, a laptop, three mobile phones, an internet dongle and two newspapers which carried the articles of HNLC, suspiciously kept in a carton, in the his house were seized by the police.
Among the six arrested were a women sympathiser who were picked up from various parts of the city, police said.
They were identified as Bakmenlang Kharpuri of Mawkhar Block 6, Goldy Khongwir, Lawanbiang Dohkrut and Jolene Hazel Khongwir of Wahiingdoh Ria Mohan Lane, Stadpyrkhat Langstieh of Lum Shyiap, Golflink and Phaiborlang Donshiew of Sngithiang, Mawprem.
