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.

Rwandan-backed M23 rebels captured the mining town of Nyabibwe in eastern Congo’s South Kivu province, violating a ceasefire they declared earlier this week, according to NBC News. The rebels now advance toward Bukavu, raising fears of further conflict after seizing the city of Goma last week.

Congolese M23 rebels are seen as they withdraw from the 3 antennes location in Kibumba, near Goma, North Kivu Province of the Democratic Republic of Congo on December 23, 2022.

The Eastern Congo rebel alliance that includes the M23 has declared a ceasefire for humanitarian reasons starting on Feb. 4, the group known as the Congo River Alliance said in a statement.

Goma remains “under occupation” by Congo’s M23 rebels and the ceasefire they announced has been broken as their forces engage in heavy fighting along the main route to South Kivu’s main city Bukavu.