Famine has spread across war-torn Sudan and is projected to expand even further, a UN-backed assessment said on Tuesday, with refugee camps and displaced communities hit particularly hard.

The Integrated Food Security Phase Classification (IPC) review, which is used by UN agencies, determined that famine had spread to two additional displacement camps in the country's west and parts of the south.

Sudan is reeling from 20 months of fighting between the Sudanese army and the paramilitary Rapid Support Forces, led by rival generals, which have led to a dire humanitarian crisis.

The war since April 2023 has killed tens of thousands of people and uprooted 12 million, creating what the United Nations has called the world's largest displacement crisis.

In its latest report on Tuesday, the IPC said 638,000 people are now facing catastrophic levels of hunger, with a further 8.1 million on the brink of famine.

UN Secretary-General Antonio Guterres expressed alarm, reiterating "his call for the parties to facilitate rapid, safe, unhindered and sustained access so that humanitarian assistance and staff can reach people in need", according to a statement.

The IPC found there was famine in three camps in North Darfur - including Zamzam, where famine had already been declared in August - and among residents and displaced communities in the Nuba Mountains, in the southern Kordofan region.

Between December and May, the IPC said that 24.6 million people representing around half of Sudan's population are projected to face "high levels of acute food insecurity".

The report said that this "marks an unprecedented deepening and widening of the food and nutrition crisis".

According to the UN's World Food Programme (WFP), some areas of "intense conflict", including parts of the capital Khartoum and the central state of Al-Jazira, "may already be experiencing famine conditions", but a lack of access to data has prevented an official classification.

Guterres, in his remarks on Tuesday, urged "an immediate cessation of hostilities to save lives and prevent the crisis... from escalating even further in 2025", his spokeswoman Stephanie Tremblay said in a statement. (AFP)