Deadly fighting has raged in the northeast African country since mid-April, when army chief Abdel Fattah al-Burhan and his former deputy Mohamed Hamdan Daglo, who commands the paramilitary Rapid Support Forces (RSF), turned on each other.
The latest in a series of ceasefire agreements enabled civilians trapped in the capital Khartoum to venture outside and stock up on food and other essential supplies.
But only 10 minutes after it ended at 6:00 am (0400 GMT) on Sunday, the city was rocked again by shelling and clashes, witnesses told AFP.
Heavy artillery fire was heard across greater Khartoum, with residents also reporting air strikes and anti-aircraft missiles. Fighting in the capital's south sent "shells landing in citizens' homes," a pro-democracy neighbourhood group reported.
The one-day lull was "like a dream" that evaporated, said Nasreddin Ahmed, a resident of south Khartoum who was awoken by the renewed fighting.
Asmaa al-Rih, who lives in the capital's northern suburbs, lamented the "return of terror" with "rockets and shells shaking the walls of houses" once again.
Clouds of smoke were also seen billowing for a fifth successive day from the Al-Shajara oil and gas facility near the Yarmouk military plant in Khartoum.
Multiple truces have been agreed and broken, including after the United States had slapped sanctions on both rival generals after a previous attempt collapsed at the end of May.
Sudan's military elites as well as Daglo amassed considerable wealth during the rule of longtime strongman Omar al-Bashir, whose government was subjected to decades of international sanctions before his overthrow in 2019.
The 24-hour ceasefire that ended on Sunday had been announced by US and Saudi mediators who warned that if it failed they may break off mediation efforts.
The two warring sides had "agreed to allow the unimpeded movement and delivery of humanitarian assistance throughout the country", the Saudi foreign ministry said on Saturday.
The mediators said in a joint statement they "share the frustration of the Sudanese people about the uneven implementation of previous ceasefires".
The fighting has gripped Khartoum and the western region of Darfur, killing upwards of 1,800 people, according to the Armed Conflict Location and Event Data Project.
Nearly two million people have been displaced, including 476,000 who have sought refuge in neighbouring countries, the United Nations says. Over 200,000 have entered Egypt, mostly by land.
At the same time, Cairo on Saturday announced it was toughening requirements for those Sudanese who had previously been exempted from visas – women of all ages, children under 16 and anyone over 50.
Egypt said the new requirements were not designed to "prevent or limit" the entry of Sudanese people, but rather to stop "illegal activities by individuals and groups on the Sudanese side of the border, who forged entry visas" for profit.