The Sudanese government is sending more troops to the restive Darfur region, following increased violence there.
Prime Minister Abdalla Hamdok said the forces would protect people during the agricultural season.
Unidentified gunmen killed more than 60 people in the region on Saturday and another 20 the day before, the UN said.
Hundreds of thousands of people have been killed in fighting between government forces and rebels since 2003. Millions have been forced to flee their homes.
In the latest uprising, several villages were burned and markets and shops were looted, the United Nations Office for the Coordination of Humanitarian Affairs (OCHA) said.
“The escalation of violence in different parts of the Darfur region is causing further displacement, compromising the agricultural season, causing loss of life and livelihoods, and fueling growing humanitarian needs,” it said in a statement.
No group has yet said that it has carried out the attacks.
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Former President Omar al-Bashir, who was overthrown last year, is wanted by the International Criminal Court (ICC) for alleged war crimes and genocide in the region.
Last week, the 76-year-old man was tried in Sudan’s capital Khartoum in connection with the 1989 military coup that brought him to power.
You could face the death penalty if found guilty.
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Bashir has already been convicted of corruption.