The UN reported in December that up to 4,000 Rwandan soldiers are fighting alongside the M23 against the Congolese army and FDLR militia group. Rwandan President Paul Kagame has denied accusations that his soldiers are in DR Congo, though he has also simultaneously sought to justify its presence and right to defend itself.

M23 fighters and Rwandan troops entered the DR Congo provincial capital of Bukavu on Friday, security and humanitarian sources said.

The Democratic Republic of Congo is in turmoil - fighters from the notorious M23 rebel group have been surging through the country's east, battling the national army and capturing key places as they go.

If the rebels capture the capital of South Kivu province, it would represent an unprecedented expansion of territory under their control Rwandan-backed M23 rebels appeared on Friday to be closing in on eastern Democratic Republic of Congo's second-largest city,