Rwanda-backed rebels appeared to be heading toward a third major city in eastern Congo, frightened residents said Tuesday, as international pressure rose over the M23's expansion in the mineral-rich region that's critical for global technology.

The UN's human rights chief accuses Rwanda-backed M23 rebels of killing children and attacking hospitals in eastern Congo. M23, having seized cities Bukavu and Goma, is accused of seeking control over Congo's mineral-rich region with Rwanda's support.

Rwanda-backed rebels captured a second major strategic city in the Democratic Republic of Congo, expanding their dominance over the country’s mineral-rich east amid the widening conflict.