Rwanda-backed rebels who captured eastern Congo's largest city said Thursday they want to take their fight to the far-off capital, Kinshasa, while Congo’s president called for a massive military mobilization to resist the rebellion and his defense minister rejected calls for talks.

The United Nations expressed deep concern at reports of M23 rebels and Rwandan troops advancing south towards the Congolese city of Bukavu on Thursday, as the militants sought also to assert their control over east Congo's largest city Goma.

The Democratic Republic of Congo's electoral body has accused the Rwandan army and M23 rebels of looting polling office facilities in Goma, a city in eastern Congo.