Two South African peacekeepers were killed after their convoy was ambushed north of Congo's eastern city of Goma.
A UN military source confirmed that two peacekeepers had been killed and said 11 people had been wounded in the shooting, three of them seriously.
The attackers were suspected of being Interahamwe, Rwandan Hutu rebels who fled into Congo after Rwanda's 1994 genocide.
Congo's lawless east has plunged into a fresh spiral of violence since renegade troops seized the town of Bukavu last week, raising fears of a wider war.