CAIRO: The UN Joint Human Rights office has received credible reports about the existence of at least 13 mass graves in Sudan’s El Geneina, a city in Darfur, and its surrounding areas, the head of the UN’s Sudan mission said on Wednesday. The mass graves contained victims of attacks by the paramilitary RSF and allied Arab militias on civilians, the majority of whom were from the Masalit community, Volker Perthes told the UN Security Council. “UNITAMS and UN colleagues are documenting these violations and recall that these acts, if verified, may constitute war crimes,” Perthes said, in an address in which he also announced his resignation as envoy. Ethnically targeted violence in El Geneina, a city in West Darfur close to the border with Chad, has escalated sharply since conflict between the RSF and Sudan’s army erupted in the capital Khartoum in mid-April.