Residents of Khartoum and adjoining Omdurman said the army had resumed air strikes overnight and into Friday morning and was using more artillery as the clashes continued but there was no sign its paramilitary enemy was retreating from city streets and homes it has occupied.
"We are suffering so much from this war," said Shehab al-Din Abdalrahman, 31, in a southern district of the capital.
"Since this morning there have been sounds of violence.Â
"We're living in terror. It is a real nightmare."
Seven weeks of warfare between the army and Rapid Support Forces have smashed up parts of central Khartoum, threatened to destabilise the wider region, displaced 1.2 million people inside Sudan and sent another 400,000 into neighbouring states.
The US and Saudi Arabia on Thursday suspended truce talks after a ceasefire they had mediated fell apart, accusing the sides of occupying homes, businesses and hospitals, carrying out air strikes and attacks and executing banned military movements.
Washington imposed sanctions on businesses belonging to the army and RSF and threatened further action "if the parties continue to destroy their country", according to a senior US official.
Sudan's ambassador to Washington, Mohamed Abdallah Idris, said the government and army remained fully committed to the truce pact and any penalties should be "imposed on the party that did not abide by what it signed" - a reference to the RSF.
The two sides have blamed each other for truce violations.
Since the overthrow of longtime ruler Omar al-Bashir in 2019, Sudan's government has been headed by a sovereign council under army chief Abdel-Fattah al-Burhan with the RSF head Mohamed Hamdan Dagalo, known as Hemedti, as his deputy.
After they went to war on April 15, Burhan said he had dismissed Hemdti from the council, and government departments have remained aligned with the army.
Outside Khartoum, the worst fighting has been in the Darfur region, where a civil war has simmered since 2003, killing about 300,000 people.
More than 100,000 people have fled militia attacks in West Darfur to neighbouring Chad since the latest fighting began, and the numbers could double in the next three months, the United Nations refugee agency said on Thursday.
Truce efforts had been aimed at delivering humanitarian aid to civilians caught in a war that has brought deadly shellfire and shooting, disabled power and water networks, ruined hospitals and hampered food supplies in an already hungry nation.
The UN's World Food Programme and its refugee agency UNHCR said continued looting was disrupting their efforts to help Sudanese, calling on all parties to respect humanitarian work.
The WFP said it had recorded losses of more than $US60 million ($A91 million) since the fighting began.
The UNHCR said two of its offices in Khartoum were pillaged and its warehouse in El Obeid was targeted on Thursday.
