KINSHASA (Reuters) - United Nations peacekeepers killed seven rebels in eastern Democratic Republic of Congo on Thursday as part of operations to tamp down rising inter-ethnic tensions in the area, the U.N. mission said on Friday.

South African troops from the U.N. Force Intervention Brigade fired on members of a primarily Kobo and Nande militia after they tried to prevent aid workers giving out food to Hutu civilians in a displacement camp in the town of Buleusa in North Kivu province, mission spokesman Charles Bambara said.

Eleven other militiamen were wounded while the rest fled, Bambara added. The U.N. troops suffered no casualties.

The U.N. intervention in Buleusa follows a week of surging tensions between Hutus and the Kobo and Nande communities after rumors spread that members of the FDLR, a Hutu militia with officers implicated in the 1994 Rwandan genocide, had infiltrated displaced persons camps.

Nande and Kobo militiamen killed at least four Hutus and burned hundreds of their huts in Buleusa on Monday, according to Samuel Ntaota, a spokesman for the local Hutu community.

Ethnic rivalries, foreign invasions and competition for mineral-rich land have stoked persistent conflict among eastern Congo's dozens of rebel groups over the last two decades, costing millions of lives.

(Reporting by Aaron Ross; Editing by Marine Pennetier and Mark Heinrich)