The estimated number of people facing acute food insecurity in Sudan has risen faster than expected to 20.3-million, or 42% of the population, as a conflict between rival military factions deepens a humanitarian crisis, a food security body said.

The worst hit areas include the capital Khartoum, the western region of Darfur, and parts of Kordofan, all of which have seen fighting, attacks and looting since the war broke out in mid-April, according to the Integrated Food Security Classification (IPC), a partnership of UN agencies, NGOs and other groups.

The conflict between Sudan's army and the paramilitary Rapid Support Forces (RSF), which erupted amid disputes over an internationally backed plan for a transition to civilian rule, has led to the displacement of more than 3-million people within Sudan and forced more than 900 000 to flee to neighbouring states.

Disruption of supply chains, population displacement, and damage to infrastructure caused by the conflict were all contributing to rising hunger, according to data released by the IPC late on Wednesday.

"The results reflect a significant increase in the expected magnitude of the food insecurity situation," the IPC said, adding the number facing acute hunger and in need of urgent support was 8.6-million than during the same period last year.

The United Nations had earlier forecast that 19.1-million people would be going hungry by August. Farmers told Reuters that their inability to plant crops could accelerate the spread of hunger.

During the harvesting season between October 2023 and February 2024 the number facing acute food insecurity is forecast to drop back to about 15-million, though that would still be the highest figure on record during that period, the IPC said.

Residents across Sudan have reported worsening conditions, including power cuts that have recently lasted for days at a time in some areas, shortages of medicine, and communications blackouts.

Aid agencies have struggled to deliver relief.

Rights group Amnesty International reported on Thursday that extensive war crimes were being committed in Sudan, with civilians killed in both deliberate and indiscriminate attacks.

Reuters reported last week that the civilian death toll in Khartoum was much higher than official figures suggest, as residents are trapped between RSF occupation on the ground and army air strikes and bombardment.