UN investigators said Monday they had found more mass graves in the central Kasai region of the Democratic Republic of Congo, where tribal militias are battling security forces.
"We have shared with the authorities the discovery of new mass graves in Grand Kasai. The number has risen from 10 to 23 mass graves in Kasai, Kasai-Central and Kasai-Oriental," senior UN human rights official Jose Maria Aranaz told AFP.
Aranaz gave no estimate of the number of bodies buried in the graves, stating that this was "a matter for the Congolese authorities".
Government spokesman Lambert Mende has acknowledged "the existence of more than three mass graves" in the region but has not identified the dead or their suspected killers.
Fighting erupted in Kasai after government forces last August killed tribal chief Jean Pierre Mpandi, also known as Kamwina Nsapu, who had launched an uprising against the government of President Joseph Kabila.
On March 22, UN investigators counted 10 mass graves connected with the conflict between security forces and militias rebelling in the name of Kamwina Nsapu, at a cost of at least 400 lives.
"We continue the work because the existence of other mass graves has been reported," said Aranaz, director of the United Nations joint human rights office (UNJHRO) in DRC.
Two UN researchers, American Michael Sharp and Swedish-Chilean dual national Zaida Catalan, were kidnapped on March 12 with four Congolese nationals. Their bodies were found in a grave 16 days later.
In another incident, national police accused followers of Kamwina Nsapu of massacring 39 police officers and looting equipment in an ambush on March 24.
DRC security forces have faced regular UN rebukes over the use of disproportionate force against the militiamen, who are armed mainly with clubs and catapults. But the Kamwina Nsapu forces have also been accused of atrocities and of recruiting child soldiers.