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.

Democratic Republic of Congo's M23 rebels are moving south towards Bukavu, the capital of South Kivu province, in what appears to be an attempt to expand their area of control in the country's east after capturing the city of Goma.

The Rwandan-backed armed group M23 moved south as it closed in on a key military airport in DR Congo on Friday, a day after pledging to take the capital Kinshasa and as international criticism mounted.