The air strikes, explosions and clashes could be heard in the south of Khartoum, and there was heavy shelling across the River Nile in parts of the adjoining cities of Bahri and Omdurman, witnesses said.
The fighting between the army and the paramilitary Rapid Support Forces (RSF) has triggered unrest in other areas of Sudan, especially in the western region of Darfur, but is concentrated in Khartoum.
It has caused a humanitarian crisis that threatens to destabilise the region, displacing more than 700,000 people inside Sudan and forcing about 200,000 to flee into neighbouring countries.
Those who have remained in the capital are struggling to survive as food supplies dwindle, health services collapse and lawlessness spreads.
Officials have recorded 676 deaths and more than 5,500 injuries, but the real toll is expected to be far higher with many reports of bodies left in the streets and people struggling to bury the dead.
“The situation is unbearable. We left our house to go to a neighbour’s house in Khartoum, escaping from the war, but the bombardment follows us wherever we go,” said Ayman Hassan, a 32-year-old resident.
“We don’t know what the citizens did to deserve a war in the middle of the houses.”
Fighting has surged both in Khartoum and in Geneina, capital of West Darfur, since the two warring parties began talks in Jeddah brokered by Saudi Arabia and the United States more than a week ago.
The talks have produced a statement of principles about providing access for aid supplies and protecting civilians, but mechanisms for setting up humanitarian corridors and agreeing to a ceasefire are still being discussed.
Both sides had previously announced several ceasefires, none of which stopped the fighting.