Rebels in Democratic Republic of Congo are closing in on a key city in the mineral-rich region aided by neighboring Rwanda’s army, the head of a peacekeeping mission told United Nations Security Council members during an emergency meeting on Sunday.

The M23 rebel group has made significant territorial gains along the border with Rwanda in recent weeks, closing in on Goma, the provincial capital.

Gunshots rang out Sunday night in the centre of the besieged Congolese city of Goma, AFP journalists heard, after the Democratic Republic of Congo accused Rwanda of sending fresh troops across the border to capture the strategic hub.