Updated

Rebels in eastern Congo have killed at least four civilians as they fled a Congolese army operation, a representative of civil society groups said Thursday.

Fighters from the Allied Defense Forces-NALU attacked three villages in region around the town of Beni on Wednesday, according to Omar Kavota, the spokesman for the Civil Society of North Kivu.

The area has been the site of repeated massacres by the rebels, who have origins in neighboring Uganda. Congo's army and U.N. peacekeepers launched an operation against the rebels in December.

The rebels were on the move, trying to avoid the offensive, when they attacked civilians with machetes who had been working in their fields. He said four bodies have been collected and five more people remain missing. Others were wounded, but he did not know how many.

Eastern Congo is home to myriad armed groups and militias, many vying for control of the region's vast mineral resources.

The U.N. peacekeeping force is authorized to help the army battle the rebels groups but has been criticized for doing too little to protect civilians. Congo President Joseph Kabila has asked for the 21,000-strong U.N. force to be cut significantly, and negotiations will begin next week on how to do that.