This despite a declaration of principle on permanent ceasefire being signed by the parties as recently as July, with the goal of signing a peace agreement on August 18.
But the fighting has since Friday intensified around the city of Mulamba in the South Kivu province. On Monday, the fighting continued.
Both sides are using heavy weapons, says a resident who was interviewed by the news agency AFP over the phone.
More than two million people have fled the violence in eastern Congo-Kinshasa since January, according to a report from the UN's humanitarian organization OCHA that was released in July.
