A rebel group that claimed to have captured the city of Goma in the eastern Democratic Republic of Congo last week has called for an immediate humanitarian ceasefire, after fighting with the Congolese military has left hundreds of people dead.

Rwandan-backed M23 rebels have seized control of the town of Nyabibwe in eastern Democratic Republic of Congo's South Kivu province, eight sources said on Wednesday - an apparent violation of a unilateral ceasefire they declared this week.

Congo’s government has described the unilateral ceasefire declared by Rwanda-backed rebels in eastern Congo as “false communication,” while the United Nations on Tuesday noted reports of heavy fighting with Congolese forces in the region.