At least 150 people have reportedly been killed in ethnic clashes in the last two days in Sudan’s Blue Nile state in the south.
The fighting is said to be the worst in recent months.
The violence broke out last week over land dispute between members of the Hausa people and rival ethnic groups, in which more than a dozen people were killed.
An overnight curfew was put in place to contain the violence.
The UN said on Thursday that it was “alarmed by violence escalation in Lagawa and conflict resurgence in the Blue Nile region”.
“Sustainable peace won’t be possible without a fully functional credible government that prioritizes local communities’ needs including security and addresses the root causes of conflict,” the United Nations Integrated Transition Assistance Mission in Sudan said in a statement.
Sudan has been grappling with political unrest and violence since last year’s military coup.