Rwanda-backed rebels who have captured eastern Congo’s largest city say they plan to take their rebellion to the capital and seek to gain political power.

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.

Members of the M23 rebel group gather to supervise Congolese potential recruits for the M23 rebel group before being taken to training centres run by M23 rebels, amid clashes between M23 rebels and the Armed Forces of the Democratic Republic of the Congo (FARDC),