A special UN Security Council meeting is under way focusing on the war in Sudan that has seen more than a million people displaced over the last five weeks.
The UN envoy to Sudan, Volker Perthes, warned of a growing ethnic dimension to the conflict between the army and the rival Rapid Support Forces (RSF).
He said it was at risk of expanding with serious implications for the region.
A seven-day ceasefire mediated by Saudi Arabia and the United States is due to come into force in a few hours.
Gunfire and explosions have continued in the capital Khartoum and there have been frequent outbreaks of violence in the western region of Darfur.