Khartoum and its sister cities Omdurman and Bahri have been rocked by fierce battles this week between the army and the paramilitary Rapid Support Forces (RSF) that have shut the city down, stranding many and causing food supplies to run short.
Early on Thursday, smoke and fires that had risen from the city in previous days had abated, live TV feeds over Khartoum showed, before the fighting erupted once again.
Gunfire was heard in Bahri and residents reported violent clashes west of Omdurman where they said the army had moved to block the arrival of RSF reinforcements.
Both sides earlier said they would respect a 24-hour ceasefire that was due to come into effect at 6pm on Wednesday, but was quickly broken by renewed fighting.
The RSF issued a statement about the breakdown in the truce, saying it came under attack in Omdurman and inflicted losses on the army in response, including shooting down two helicopters.
Reuters could not independently verify the RSF's claims.
Some of the most intense fighting has been focussed around the compound housing the army HQ and the residence of Sudan's military ruler, General Abdel Fattah al-Burhan.
The army controls access to Khartoum and appeared to be trying to cut off supply routes to RSF fighters, residents and witnesses said.
International powers, struggling to evacuate citizens after the airport and several districts housing embassies were caught up in the violence, have been pushing repeatedly for truces, to little effect.
More people have been leaving the capital with most able to pass but some stopped at checkpoints, according to residents and social media posts.
The fighting has been raging since Saturday morning, cutting power and water supplies in many places during the final days of Ramadan, when Muslims fast from dawn to dusk.
The power struggle between Burhan and RSF leader General Mohamed Hamdan Dagalo, widely known as Hemedti, was triggered by an internationally-backed plan to form a new civilian government and integrate Hemedti's RSF into the regular military.
It has dashed hopes for progress towards democracy in Sudan, risks drawing in its neighbours and could play into regional power plays. Sudan sits strategically between Egypt, Saudi Arabia, Ethiopia and Africa's volatile Sahel region.
Burhan heads a ruling council installed after the 2021 military coup and the 2019 ouster of veteran autocrat Omar al-Bashir, while Hemedti, who analysts say may command more than 100,000 fighters, was his deputy on the council.
At least 270 people have died and 2600 have been injured, Sudan's health ministry estimates. Nine hospitals have been hit by artillery and 16 had to be evacuated, the Sudanese Doctors' Union said, with none operating fully inside the capital.
Prices for petrol and for fresh food have been hiked sharply by some sellers.
The two military factions are also fighting in other parts of Sudan, including the western Darfur region, site of a brutal conflict that escalated after 2003 and displaced more than two million people.
Even before the conflict, about one quarter of Sudan's population was facing acute hunger. The World Food Program halted one of its largest global aid operations in the country on Saturday after three of its workers were killed.
