The United Nations is formally ending its support for a Congo military offensive against a rebel group after two Congolese generals linked to human rights violations were picked to lead the operation.

A U.N. official says letters are being sent this weekend to Congolese authorities about the cessation of support. The official spoke on condition of anonymity because of the sensitivity of the issue.

The U.N. has repeatedly warned Congo in recent days over the generals, saying they are known to be heavily involved in human rights violations and should be replaced before the U.N. supports the offensive.

The U.N. estimates that 2,000 FDLR rebel fighters remain in Congo. They include Hutus who committed the 1994 Rwanda massacres.

The U.N. has said it continues to support other Congolese military operations.