GENEVA (Reuters) - The people of Sudan are at "imminent risk of famine", United Nations agencies said on Friday, more than a year into a war between the army and the paramilitary Rapid Support Forces (RSF).

Around 18 million people are already acutely hungry, including 3.6 million children who are acutely malnourished, according to a joint statement by U.N. chiefs including Volker Turk, the U.N. High Commissioner for Human Rights

"Time is running out for millions of people in Sudan who are at imminent risk of famine, displaced from their lands, living under bombardments, and cut off from humanitarian assistance," the statement added.

Fighting broke out in the capital Khartoum in April 2023 and quickly spread across the country, reigniting ethnic bloodshed in the western Darfur region and forcing millions to flee in the world's largest displacement crisis.

"Without an immediate and major step change, we will face a nightmare scenario: A famine will take hold in large parts of the country," read the statement also signed by U.N. aid chief Martin Griffiths.

The war broke out as long-simmering tensions over integrating the RSF with the army came to a head. The U.N. special adviser on the prevention of genocide said last week there was a risk of genocide in parts of Darfur.

A U.N.-backed report said in March that immediate action was needed to "prevent widespread death and total collapse of livelihoods and avert a catastrophic hunger crisis in Sudan".

(Reporting by Gabrielle Tétrault-Farber; Editing by Andrew Heavens)