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.

The United States, France and Britain pressured Rwanda on Sunday over its support for rebels rapidly closing in on eastern Congo's largest city, as government forces struggled to halt an offensive that has forced thousands of civilians to flee.