The United Nations expressed deep concern at reports of M23 rebels and Rwandan troops advancing south towards the Congolese city of Bukavu on Thursday, as the militants sought also to assert their control over east Congo's largest city Goma.

Rebels backed by Rwanda captured more towns in eastern Congo as fighters moved beyond the key city of Goma in an apparent attempt to expand their control in the conflict-battered region

Many Congolese see the rebel advance as an invasion of their country by a foreign power in an attempt to seize land and Congo’s valuable rare minerals.