While Saturday marked the calmest day since the conflict began, Sunday’s fighting has been the “most fearless”, with residents sheltering in place for safety, she added.

Witnesses said fighting resumed in the north of Omdurman, in el-Geneina near the border with Chad, and in el-Obeid, the capital of North Kordofan state, southwest of Khartoum.

The United States and Saudi Arabia-brokered ceasefire was set in order to facilitate the safe passage of desperately needed humanitarian aid across the country. It was also hoped that it would halt the fighting that has been raging since April 15.

Morgan said that during the 24-hour truce, some aid groups were able to reach those in need, with people in the southern part of the capital also able to leave their homes to replenish their stock of essential commodities.

But in the northern part of the capital, she said people remained trapped with no assistance.

Darfur

Meanwhile, the situation in West Darfur is being described as “catastrophic”, Morgan reported.

In el-Geneina in particular – which has been experiencing a communication outage for weeks – there have been new waves of attacks by Arab nomadic tribes with ties to the RSF.

These militias, Morgan said, are targeting people based on ethnicity. The West Darfur Doctors’ Syndicate has called the killings, in which more than 1,000 people have died, equivalent to genocide.

See inside a refugee camp for Sudanese finding safety in Chad

The violence has led to people fleeing to neighbouring Chad over the past weeks, a harrowing and risky journey, according to Al Jazeera’s Zein Basravi in the Chadian city of Adre on the border with Sudan.

Abdulkareem Haroon, a man who fled el-Geneina to Adre, said he was beaten and whipped and lost his brother on the journey.

“I don’t know if they killed him or have taken him,” Haroon told Al Jazeera.

El-Obeid, on a major route to Darfur, is said to be under a state of siege, with residents saying supplies of food and medicine are cut off.

“The situation is difficult. The RSF are spread out on the roads between the villages and they are looting, and there are gangs looting everywhere. Moving from place to place became dangerous,” North Kordofan resident Mohamed Salman told the Reuters news agency.

“We don’t know how we’ll plant or how we’ll live in this situation.”

The wider Kordofan region is an important agricultural area, a source of livestock, oilseeds and gum Arabic.

More than 1.4 million people have been displaced within Sudan and a further 476,800 have fled to neighbouring countries, most of whom are already struggling with poverty and internal conflict, according to estimates from the International Organization for Migration.

About half of those fleeing are heading north to Egypt. On Saturday, Egypt toughened its visa rules for Sudanese nationals fleeing the war, requiring visas before crossing the border, and reversing an exemption for women and children.