Rwandan-backed M23 rebels in Democratic Republic of Congo were moving south on Wednesday towards Bukavu, the capital of South Kivu province, in what appeared to be an attempt to expand their area of control in the country's east after capturing the city of Goma.

U.S. Secretary of State Marco Rubio called for a urgent cease-fire in the conflict in eastern Democratic Republic of Congo saying Washington was "deeply troubled" by a recent escalation in the fighting.

The rebels, which Rwanda denies supporting, have long been funded at least in part by the illicit mineral trade.

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.

M23 rebels in the Democratic Republic of Congo have seized Goma and are advancing towards Bukavu, amplifying tensions in the region. The conflict, fueled by resource control, has overwhelmed local hospitals and forced Romanian mercenaries to withdraw.

Rwandan backed rebels have entered the city of Goma, a key city in neighboring Democratic Republic of Congo. Could the mineral rich region be in danger of tipping into all out regional conflict?

Despite a flurry of diplomatic activity, there were growing signs the rebels were taking over the running of east Congo’s largest city

A lightning advance in Congo's mineral-rich eastern borderlands is set to boost the M23 rebellion's illegal mining revenues, with analysts predicting a further surge in illicit trade in minerals including coltan and gold through neighbouring Rwanda.

Rwanda-backed fighters advanced on a second front in their offensive across eastern DR Congo on Wednesday after seizing control of most of the key city of Goma during heavy fighting with the Congolese military.

Kenya has announced a virtual crisis summit, but Congolese state media says President Felix Tshisekedi will not attend.

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.