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

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.

M23 is the latest in a long line of Rwandan-backed rebel movements to emerge in Congo's volatile eastern borderlands following two successive wars stemming from Rwanda's 1994 genocide. Rwanda denies supporting the well-trained and heavily armed Tutsi-led group.