RUTSHURU, Congo (AP) — A new rebellion in Congo’s east, known as the M23, is consolidating its power over the territory it conquered over five months and could pose a serious threat to the Congolese government as a U.N. chief says the group has set up a parallel government.

The rebellion began in April when a group of senior commanders defected from the regular army, following rumors that one of the leaders, Bosco Ntaganda, would be arrested. He is wanted by the International Criminal Court for war crimes. After just three months of fighting against their former comrades, the group took over a large part of Rutshuru territory at the border with Rwanda and Uganda. It is now consolidating its power in Rutshuru and proceeded to appoint a handful of “administrative heads.”