Martin Griffiths, travelling with immediate effect, says humanitarian crisis ‘rapidly deteriorating’ with people struggling to get food and water.

“The scale and speed of what is unfolding in Sudan is unprecedented in the country,” Guterres wrote on Twitter as he announced his decision on Sunday. “In light of the rapidly deteriorating humanitarian crisis, I am sending @UNReliefChief [Martin Griffiths] to the region immediately.”

In a separate statement, Griffiths said that Sudan’s humanitarian situation was “reaching breaking point”, essential items were becoming increasingly scarce, especially in Khartoum, and people were struggling to find food, water and fuel. The rising cost of transport was also making it impossible for the poorest to reach safer locations, he added.

“I am on my way to the region to explore how we can bring immediate relief to the millions of people whose lives have turned upside down overnight,” he said, reiterating the need for the fighting to stop.

The army and the paramilitary Rapid Support Forces (RSF) both said they would extend the much-breached ceasefire for a further 72 hours, with the RSF saying its decision was “in response to international, regional and local calls”.

The army said it hoped what it called the “rebels” would abide by the deal, but it believed they intended to continue their attacks. The parties have kept fighting through a series of ceasefires secured by mediators, including the United States.

More than 500 people have been killed and tens of thousands forced to leave their homes within the country or across borders since a long-simmering dispute between the armed forces and the RSF erupted into violence on April 15.

The fighting in Khartoum has so far seen RSF forces fan out across the city, and the army using mostly drones and fighter jets to target the group, pounding the city from the skies.

Many foreign governments have scrambled to evacuate their citizens from the country.

Griffiths said the UN’s attempts to provide relief had been complicated by the looting of humanitarian offices and warehouses which had “depleted most of our supplies”, and that other options were being urgently explored.

Sudanese journalist Mohamed Alamin Ahmed, who is in Khartoum, told Al Jazeera that people had many reasons to escape the capital.

“People are fleeing Khartoum not only because of the humanitarian situation and the bombs that have fallen on houses of civilians because of random shelling and air strikes, but also because of looting civilians in the streets, and even inside their houses,” he said.

He also noted the constraints on healthcare after hospitals came under fire.

Five containers of intravenous fluids and other emergency supplies were docked in Port Sudan awaiting clearance by authorities, he added.

The conflict has derailed an internationally backed political transition aimed at establishing a democratic government in Sudan, where former ruler President Omar al-Bashir was toppled in 2019 after three decades in power.