Sudan’s war has forced 100,000 people to flee over its borders and fighting now its third week is creating a humanitarian crisis, UN officials said on Tuesday as gunfire and explosions echoed across the capital despite another ceasefire deal.

The conflict risks morphing into a broader disaster as Sudan’s impoverished neighbours deal with a refugee crunch and fighting hampers aid deliveries in a nation where two-thirds of people already rely on some outside assistance.

Egyptian President Abdel-Fattah al-Sisi said Cairo would provide support for dialogue in Sudan between the rival military factions but was also “being careful about not interfering in their domestic matters”.

“The entire region could be affected,” he warned in an interview with a Japanese newspaper on Tuesday as an envoy from Sudan’s army chief, who leads one of the warring sides, met Egyptian officials in Cairo.

UN officials had said UN aid chief Martin Griffiths aimed to visit Sudan on Tuesday, but the timing was still to be confirmed.

The UN’s World Food Programme said on Monday it was resuming work in the safer parts of the country after a pause earlier in the conflict, in which some WFP staff were killed.

“The risk is that this is not just going to be a Sudan crisis, it’s going to be a regional crisis,” said Michael Dunford, the WFP’s East Africa director.

The commanders of the army and paramilitary Rapid Support Forces (RSF) who previously shared power as part of an internationally backed transition towards free elections and civilian government show no sign of backing down, yet neither seem able to secure a quick victory. That has raised the spectre of a prolonged conflict that could draw in outside powers.

Early on Tuesday, black smoke could be seen hanging over the capital Khartoum, which lies at the confluence of the Blue and White Nile rivers. Air strikes hit Bahri, on the east bank, while clashes flared in Omdurman to the west, witnesses said.

Hundreds of people have died in the fighting that pits the army under General Abdel-Fattah al-Burhan against the RSF under General Mohamed Hamdan Dagalo, also known as Hemedti. Each has blamed the other for the violation of a series of ceasefires.

The army has used airpower against RSF units dug into residential areas of Khartoum, damaging swathes of the capital area and reigniting conflict in the Darfur region.