The U.N. says Rwanda-backed rebels are expanding their presence in eastern Congo after capturing the region’s major city

Rwanda, which diplomats say backs M23 fighters who seized Goma in Democratic Republic of Congo this week, called on Wednesday for a ceasefire across eastern Congo and for Congo to negotiate with the rebels while denying Rwandan troops were involved.

Rwanda-backed M23 rebels are moving “rapidly” through South Kivu province toward the city of Bukavu in eastern Democratic Republic of Congo, the United Nations said.

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.