At least 22 people were killed as a result of fighting between Christian militias and Muslims this week in the Central African Republic town of Bria, the country's UN mission said on Saturday.
Those killed included 17 civilians while the clashes also left 36 injured and forced some 10,000 others to flee.
The clashes come amid a week of intense violence between the Anti-Balaka Christian militias and Muslims from the former Seleka rebel coalition that overthrew President Francois Bozize in 2013.
"The fighting between armed groups in Bria and elsewhere in eastern CAR must stop," Diane Corner, the deputy head of the peacekeeping mission, MINUSCA, said in a statement.
"These appalling acts of violence committed by armed groups over the last week have killed scores of innocent Central African men, women and children, deprived families of their homes and citizens of their livelihoods," she said.
The rival factions fought over the northeastern town of Bria's airstrip on Friday and looting forced humanitarian workers to seek refuge inside the MINUSCA base there.
UN soldiers have also reinforced their positions in the towns of Bangassou and Alindao, which have been hit by violence this week as well.
Red Cross workers said on Wednesday they recovered 115 bodies in Bangassou, a diamond mining hub, after several days of fighting there.