The M23 rebel movement has advanced on Goma, capital of the Democratic Republic of the Congo province of North-Kivu.
The head of the local UN peacekeeping mission said Sunday that the airport into the city was no longer available for humanitarian operations and evacuations, with M23 declaring airspace over Goma closed.
Hundreds of thousands of residents of the city of one million are thought to have fled or been displaced.
Two South African UN peacekeepers and seven more from the SADC’s DRC contingent were reported killed in fighting with rebels.
The DRC has broken off relations with Rwanda amid the escalation following long-running suspicions by Kinshasa, the UN, the US and its allies that the neighboring nation has helped fuel the conflict, and is now directly involved in fighting.
M23 is now in control of a major mining operation extracting coltan, a key element used in smartphones, laptops and other electronics.
The DRC is home to an estimated $24-$35 trillion in untapped mineral and energy wealth, but is also one of the five poorest countries in the world, in part thanks to decades of colonialism, imperialism and meddling by foreign powers.