"Active zones of combat have spread to all quarters of the city, all the neighborhoods of the city," Lemarquis, the deputy U.N. envoy and top U.N. aid official in the DRC, told reporters in New York via video from Kinshasa.

Troops from Democratic Republic of Congo and Rwanda have been firing at each other across their shared border in the eastern Congolese city of Goma, where Rwandan-backed rebels launched an offensive,

The rebel militia M23, backed by Rwanda, captured Goma, a major city in eastern Democratic Republic of Congo, on January 27, marking a significant escalation in the conflict. M23 had briefly seized the city in 2012 but had been dormant for years.