Rwandan-backed M23 rebels asserted their control over east Congo's largest city Goma on Thursday by calling on residents to resume normal life, even as the group clashed with Congolese troops as they tried to take more territory.

Congo has severed diplomatic ties with Rwanda as fighting between Rwanda-backed rebels and government forces rages around the key eastern city of Goma.

Goma is the capital of the conflict-battered North Kivu province, whose minerals are critical to much of the world’s technology. By capturing Goma, the rebels and their Rwandan allies would gain control of key border crossings, transport routes and a major airport – all of which are crucial to the lucrative mineral trade.

Rwandan President Paul Kagame blasted criticism of his country's role in eastern Democratic Republic of Congo where rebels his government backs have seized its largest city, saying Kigali is prepared for "confrontation" if necessary.