KINSHASA, Congo – Attackers ambushed U.N. peacekeepers on patrol in northeastern Congo on Friday, killing several of them, a U.N. spokesman said.

The spokesman, Mamadou Bah, didn’t give the troops’ nationalities or say how many were killed.

About 16,000 U.N. peacekeepers are overseeing a transition toward peace in Congo, where a six-nation 1998-2002 war 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 and Lendu tribes. During the war, neighboring Uganda and Rwanda armed the Hema and Lendu militias, mainly to wrest control of the mineral-rich territory. The two sides eventually turned on one another.