A major offensive by Rwandan-backed M23 rebels in east Democratic Republic of Congo appeared to have stalled on Saturday after the army took back some ground, two civil society sources and a local official said.

Rwanda-backed rebels were quickly expanding their presence in eastern Congo after capturing Goma, the region's major city, the U.N. said Friday, also expressing concerns over executions it learned were carried out by the rebels following a major escalation of their yearslong rebellion.

Rwanda-backed M23 rebels are moving “rapidly” through South Kivu province toward the city of Bukavu in eastern Democratic Republic of Congo, the United Nations said.