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.

The United States urged the United Nations Security Council on Tuesday to consider measures to halt an offensive by Rwandan troops and M23 rebel forces in eastern Democratic Republic of Congo as a conflict there escalates.

As the fighting raged on with the M23 rebels Saturday, the Congolese army recaptured the villages of Sanzi, Muganzo and Mukwidja in South Kivu's Kalehe territory, which had fallen to the rebels earlier this week, according to two civil society officials. who spoke to The Associated Press on the condition of anonymity over fear for their safety.