Rwanda will not engage in any talks with M23, Mushikiwabo said. "Our interlocutor is the government of the DRC," she said.

Mushikiwabo said Rwanda would close the border crossing if asked to by the Congolese government, but that such a move could have humanitarian consequences.

Tens of thousands of Congolese, already displaced by previous rounds of fighting in the volatile region, have fled camps around the edges of Goma, according to UNICEF and the medical charity Doctors Without Borders.