Twenty people died in ethnic clashes last week in the troubled central Kasai region of Democratic Republic of Congo, the United Nations said Wednesday.

The UN’s DR Congo mission, MONUSCO, said in a statement that the clashes took place on April 19 east of the Kasai capital, Tshikapa, between members of the Lulua-Luba and Chowe-Pende communities, killing 20 Chowe-Pende people.

The Chowe-Pende consider themselves indigenous to the Kasai region and accuse the Lulua-Luba from the neighboring Kasai region of supporting the Kamwina Nsapu militia. The latter claim their authority from chief Kamwina Nsapu who was killed in the region in August 2016 by police after a rebellion against the Congolese authorities.

Kasai has since been shaken by violence between security forces and militias in which around 100 people died, including two UN experts — American Michael Sharp and dual Swedish-Chilean national Zaida Catalan.

The Kamwina Nsapu rebellion has been accused by the UN of numerous atrocities and recruiting children. The security forces, meanwhile, are blamed by the UN for making disproportionate use of force against militia armed mainly with sticks and stones.