The United Nations meanwhile said the battle for the key city of Goma, which the M23 and Rwandan troops seized last week, had left at least 2,900 people dead - far higher than the previous death toll of 900.

The capture of Goma, the main city in eastern Democratic Republic of the Congo, last week by the M23 rebel group follows a three-year insurgency heavily supported by neighbouring Rwanda despite its awful impact on millions of Congolese civilians.