Hunger and disease are spreading in war-torn Sudan, with famine already present in several areas, 25 million people acutely food insecure and nearly 100,000 cholera cases recorded since last July, the World Health Organisation said on Friday.

Sudan's conflict between the army and rival Rapid Support Forces has displaced millions and split the country into rival zones of control, with the RSF still deeply embedded in western Sudan, and funding cuts are hampering humanitarian aid.

"Relentless violence has pushed Sudan's health system to the edge, adding to a crisis marked by hunger, illness and despair," WHO Senior Emergency Officer Ilham Nour said in a statement.

"Exacerbating the disease burden is hunger," she said, adding that about 770,000 children under 5 years old are expected to suffer from severe acute malnutrition this year.

Cholera has also hit a camp for Darfur refugees in neighbouring eastern Chad, the United Nations refugee agency said on Friday.

An outbreak in the Dougui refugee settlement has so far resulted in 264 cases and 12 deaths, said Patrice Ahouansou, UNHCR's situation coordinator in the region, leading the agency to suspend the re-location of refugees from the border with Sudan to prevent new cases.

"Without urgent action, including enhancing access to medical treatment, to clean water, to sanitation, to hygiene, and most important, relocation from the border, many more lives are on the line," Ahouansou told a briefing in Geneva.