Democratic Republic of Congo President Felix Tshisekedi has vowed “a vigorous and coordinated response” against a rebel alliance that has besieged swaths of the nation’s mineral-rich east and forced hundreds of local troops and foreign mercenaries to surrender.

The weeks-long march of the M23 armed group has prompted calls for crisis talks, as well as rising international criticism and warnings of a looming humanitarian crisis.

DR Congo President Felix Tshisekedi insisted his troops were mounting a "vigorous" response to Rwanda-backed fighters advancing in the country's perennially troubled east and slammed the international