The UN human rights chief accused Rwanda-backed rebels who seized a second major city in eastern Democratic Republic of Congo (DRC) of killing children and attacking hospitals and warehouses storing humanitarian aid.

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

Boat traffic returned to eastern Democratic Republic of Congo's Lake Kivu on Tuesday as ports re-opened in two cities which have fallen to M23 rebels, a development the United Nations said could facilitate access to humanitarian aid after weeks of fighting and looting.