Chaotic scenes have been unfolding in Bukavu in eastern Democratic Republic of Congo as the M23 rebel group continues its offensive in the region. On Saturday there were reports of sporadic gunfire and widespread looting in the city, including at a World Food Programme depot, with residents sheltering in their homes.

"The fighting that is raging in South Kivu — as a result of the continuation of the M23 offensive — threatens to push the entire region over the precipice," Guterres said without mentioning Rwanda. "And the sovereignty and territorial integrity of the DRC must be respected," Guterres added.

Nearly three thousand people have been killed in the city of Goma in the eastern Democratic Republic of Congo, according to the United Nations, after the provincial capital was captured by rebels following days of fierce fighting with the Congolese army.