Explosions and gunfire rang out on the deserted streets of Khartoum, according to witnesses.
Pro-democracy medics said early Sunday the ongoing clashes had killed at least 56 civilians.
"The total number of deaths among civilians reached 56," the Central Committee of Sudan Doctors said. It said there were "tens of deaths" among security forces not included in that death toll, and around 600 wounded.
The United Nations' food agency on Sunday said it was suspending work in country after three staff were killed in the restive Darfur region.
"While we review the evolving security situation, we are forced to temporarily halt all operations in Sudan," Cindy McCain, executive director of the World Food Program, said in a statement.
The Sudanese army approved a proposal from the U.N. to open a safe passage for urgent humanitarian cases for three hours every day starting from 1600 local time (1400 GMT) on Sunday, the army said in a statement.
The army confirmed however that it will reserve the right to react if "the rebellious militia commits any violations."
The paramilitary RSF Saturday claimed to have seized the presidential palace, army chief's residence, state television station and airports in Khartoum, the northern city of Merowe, El Fasher and West Darfur state.
The army denied the claims, and in a late Saturday statement, the Sudanese air force urged people to stay indoors as it continued air strikes against bases of the paramilitary Rapid Support Forces (RSF).
Violence erupted after weeks of deepening tensions between military leader Abdel Fattah al-Burhan and his deputy, paramilitary commander Mohamed Hamdan Daglo, over the planned integration of Daglo's RSF into the regular army.
The integration was a key element of talks to finalize a deal that would return the country to civilian rule and end the political-economic crisis sparked by the military's 2021 coup.
Created in 2013, the RSF emerged from the Janjaweed militia that then-president Omar al-Bashir unleashed against non-Arab ethnic minorities in the western Darfur region a decade earlier, drawing accusations of war crimes.
U.N. Secretary-General Antonio Guterres called for "an immediate cessation of hostilities" and discussed ways to de-escalate with the Egyptian President Abdel Fattah al-Sisi and African Union Chairman Moussa Faki.
He also spoke with Burhan and Daglo urging them "to return to dialogue."
The Arab League, following a request by Egypt and Saudi Arabia, is scheduled to hold an urgent meeting Sunday to discuss the situation in Sudan.
In a joint call, the Saudi and United Arab Emirates foreign ministers, along with US Secretary of State Antony Blinken, emphasized "the importance of stopping the military escalation," the Saudi ministry said.
This report was sourced from Reuters and Agence France-Presse.
