"We will blast serially all government (including Congress) offices in all the five Districts of Garo Hills. Now the ball is in government court to decide whether they stop or continue with police operations," GNLA said in a statement.
The outfit also demanded immediate release of their arrested chairman Champion Sangma and general secretary Dalbin N Marak.
The hill storm operation of the police was aimed at flushing out militants from their hideouts in the jungle and would continue for another month or two, the police said.
Eight weapons, 220 rounds of ammunition, five Rocket Launcher Shells and other explosive materials were recovered during the operation, the police said.