War erupted in Sudan one year ago between the Sudanese army (SAF) and paramilitary Rapid Support Forces (RSF), creating the world's largest displacement crisis.
UN political affairs chief Rosemary DiCarlo told the UN's 15-member Security Council that clashes between RSF and SAF-aligned members of the Joint Protection Forces were nearing El Fasher, the capital of North Darfur.
"Fighting in El Fasher could unleash bloody intercommunal strife throughout Darfur," DiCarlo said on Friday, echoing a warning by UN Secretary-General Antonio Guterres on Monday.
The UN has said nearly 25 million people, half of Sudan's population, need aid and some eight million have fled their homes.
"The violence poses an extreme and immediate danger to the 800,000 civilians who reside in El Fasher," said the UN aid operations director, Edem Wosornu.
"And it risks triggering further violence in other parts of Darfur – where more than nine million people are in dire need of humanitarian assistance," she said.
A United Nations-backed global authority on food security said late last month that immediate action is needed to "prevent widespread death and total collapse of livelihoods and avert a catastrophic hunger crisis in Sudan."
Donors pledged more than $US2 billion ($A3.1 billion) for war-torn Sudan at a conference in Paris on Monday.
