About 1,300 civilians have been killed in conflicts across the Democratic Republic of the Congo while more than half a million people were displaced by violence in a matter of months, the United Nations said on Friday.
UN rights chief Michelle Bachelet warned some of the massacres and attacks behind the killings and displacement "may amount to crimes against humanity and war crimes".
Her office said in a statement the number of victims had soared in recent weeks as separate conflicts in three eastern provinces - Ituri, North Kivu and South Kivu - spread "with disastrous repercussions for the civilian population".
Armed groups, it said, committed massacres and atrocities while government forces also committed grave violations.
"I am appalled by the increase in brutal attacks on innocent civilians by armed groups, and by the reaction of the military and security forces who have also committed grave violations, including killings and sexual violence," Bachelet said.
"These are not only reprehensible and criminal acts, but they also break the trust between people and the state representatives, both security and political."
The violence has forced hundreds of thousands of people to flee.
Military operations and retaliatory attacks against civilians by armed groups have displaced more than 400,000 civilians in North Kivu since last September, while some 110,000 people, mainly women and children, have fled violence in South Kivu since January, said Marta Hurtado, a spokeswoman for the UN rights office.
In South Kivu, the displacement has significantly picked up since March, she added.