KINSHASA, Congo (AP) — U.N. peacekeepers and the Congolese army have launched an operation against rebels in the country’s east blamed for a series of attacks in recent months.

Lt. Col. Felix Prosper Basse told reporters Wednesday that the operation began Saturday in the region around the town of Beni. A series of rebel attacks in that region has killed more than 250 civilians in the last two months, according to a local civil society group.

The attacks have been blamed on the Allied Defense Forces rebels. Eastern Congo is home to a myriad of armed groups and militias, many vying for control of the region’s vast mineral resources.

The U.N. peacekeeping force is authorized to battle the rebels groups but has been criticized for doing too little to protect civilians.