Speaking during a press briefing held in Geneva on the conflict's impact in the East African nation, Dominique Hyde, the UNHCR's director of external relations said hostilities "erupted without warning."
Hyde, who recently visited Sudan's White Nile state which borders South Sudan, warned the situation is dire.
"What I saw was despair, was unimaginable humanitarian needs and fear in so many peoples’ eyes," Hyde said.
According to the International Organization for Migration, or IOM, fighting between the Sudanese Armed Forces, SAF, and the paramilitary Rapid Support Forces, RSF, has displaced over 7.1 million people since April.
The IOM said in a statement that 3.8 million of the newly displaced are from River Nile, East Darfur, Northern, South Darfur, Sennar and White Nile states.
Hyde stressed the importance of the international community paying attention to Sudan.
"It is shameful the atrocities that were committed 20 years ago in Darfur can still be happening again today with such little attention," she said. "The recent fighting in Darfur and the Darfur region has caused even more displacement with thousands of people struggling to find shelter and many people sleeping under trees by the roadside."
Hyde says there have been shocking accounts of widespread rape and sexual violence in Darfur, Khartoum and other areas of Sudan.
The U.N. human rights chief, Volker Turk, has called on senior officials on both sides of the conflict to issue urgent and clear instructions to their forces demanding zero tolerance of sexual violence.
Sudan's rival forces took steps towards addressing the conflict Tuesday as Saudi Arabia brokered cease-fire negotiations.
A deal announced by the country's national news agency, the Saudi Press Agency, said the army and RSF has committed to easing humanitarian aid deliveries.
Despite the announced success, the deal does not include a cease-fire and as such is not expected to lessen the fighting.
Some information in this article was sourced from Reuters.