The attack — one of the deadliest on the 16,000-member U.N. mission in Congo — occurred near the town of Kafe, 20 miles northwest of Bunia, capital of lawless Ituri province (search), U.N. spokesman Mamadou Bah said.
The U.N. peacekeepers are overseeing a transition toward peace in Congo, where a six-nation war in 1998-2002 left some 3 million dead, most from hunger and disease.
Since 1999, fighting in the vast northeastern district of Ituri has killed more than 50,000 and forced 500,000 to flee their homes, U.N. officials and human rights groups say.
The fighting is mainly between armed militia of the Hema (search) and Lendu (search) tribes. During the war, neighboring Uganda (search) and Rwanda (search) armed the Hema and Lendu militias, mainly to wrest control of the mineral-rich territory. The two sides eventually turned on one another.