The 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 latest advances are part of a major escalation of a decades-old conflict over power, identity and resources that has killed hundreds of thousands of people and displaced more than 1 million since its recent resurgence.

What is happening in Goma?