The light infantry battalion had been supporting operations against the Lord's Resistance Army, Stars and Stripes reported.
A U.N. official said the 391st battalion, with about 750 troops, has been redeployed from Dungu to Goma, the capital of the North Kivu province, believed to be under threat from the rebel group M23.
Fighting between Congolese forces, known by the French acronym FARDC, and M23 rebels has displaced more than 220,000 people, the United Nations said. Stars and Stripes said many refugees have fled to neighboring Rwanda and Uganda.
The United Nations condemned recent attacks in the eastern region by M23, composed of former government soldiers.
"The 391 FARDC has been redeployed from Dungu to Goma, not to back-up U.N. forces, but to replace FARDC troops that had been deployed in Goma, which had been defeated by the M23 armed group in North Kivu," Fernando Falcon of the U.N. Office of the Special Representative for Children and Armed Conflict said in a statement.
The U.N. Security Council Monday expressed "deep concern with the sharply deteriorating situation in the North Kivu province of the Democratic Republic of the Congo and the worsening of the humanitarian situation in the eastern part of the Democratic Republic of the Congo, the increasing number of displaced persons and refugees and reports of both sexual violence and the use of child soldiers."