With a humanitarian ceasefire set to expire on Monday evening, fighting had already resumed in Sudan. International agencies are still struggling to deliver aid despite the week-long truce.
Residents reported gunshots in the capital, Khartoum, hours before the ceasefire was set to run out at at 9:45 pm local time.
Locals told AFP they could hear street battles and artillery fire.
The city has been turned into a war zone, with thousands of families left short of food, water and electricity.
The United States and Saudi Arabia, which brokered the the seven-day truce, called for it to be extended to allow the delivery of urgent aid.
But after repeated breaches by both sides, they said in a joint statement, no humanitarian corridors had been secured.
Fighting spreads to Darfur
In six weeks of fighting between Sudan’s military and a rival paramilitary force, hundreds of thousands of people have fled the capital for the rest of the country or into neighbouring Egypt, Chad, Central African Republic and South Sudan.
The violence has also spread to other states, including Darfur, on the western border with Chad.
The governor of Darfur, a former rebel leader allied with the military, on Sunday called on civilians to take up arms.
This came after calls from the army for reservists and pensioners to arm themselves, stoking fears of an escalation into civil war.
According to Toby Harward, principal situation coordinator in Darfur for the United Nations refugee agency UNHCR, continued fighting in the region "blatantly disregards ceasefire commitments".
In El Fasher in North Darfur, intermittent fighting between Sudanese armed forces and the paramilitary Rapid Support Forces has seen civilians killed over the last few days, Harward said.
Homes have been looted and tens of thousands newly displaced in the already war-ravaged region.
Humanitarian crisis
The persistent fighting has impeded the delivery of essential humanitarian aid, upon which 25 million people – over half the population – now rely to survive, according to the UN.
The UN sounded the alarm again on Monday, saying Sudan has become one of the highest-alert areas for food insecurity and requires "urgent" action from the international community.
The International Organisation for Migration says the conflict has displaced more than a million people inside Sudan, with a further 319,000 people seeking refuge over the border in Egypt, South Sudan and Chad.
At the Chadian border, UNHCR reported that the number of refugees arriving had now surpassed 90,000.
South Sudan refugees forced to return
More than 72,000 refugees from South Sudan have also been forced to leave Sudan and return to the country they had fled.
"From Khartoum, I wanted to go and study medicine in Cairo," 20-year-old Bolis David told RFI's reporter Florence Miettaux in the South Sudanese border town of Renk.
"But because of the crisis, I was forced to come here and change my plans. I want to go to Malakal [in South Sudan] and then go to university in Juba."
"When I was in Khartoum I was a student and I had ambitions," said another returnee, 25-year-old Charles Williams.
"If only the government could look after us, I could pursue my dreams."
Aid agencies have warned that with the rainy season approaching in June, parts of Sudan will become inaccessible, while the risk of cholera, malaria and waterborne diseases will rise.
Facing severe shortages of supplies and staff, Doctors Without Borders said that they might be forced to suspend "life-saving activities" if humanitarian corridors do not materialise.
At least 1,800 people have been killed in the conflict since 15 April.
(with AFP)
