Shelling and aerial bombardments rocked the Sudanese capital Thursday after at least 18 civilians were killed in a strike on a Khartoum market the day before.
For more than six weeks, Khartoum and other parts of the country have been gripped by bloody warfare between the army and the paramilitary Rapid Support Forces (RSF).
The army on Wednesday blasted RSF bases in Khartoum after pulling out of the talks in the Saudi city of Jeddah, accusing its rival of violating a cease-fire that was meant to allow aid deliveries.
"Eighteen civilians were killed and 106 wounded" by army artillery fire and aerial bombardments Wednesday on a market in southern Khartoum, a committee of human rights lawyers said.
The toll was confirmed by a neighborhood group that organizes aid, which said the situation was "catastrophic" and appealed for help from doctors and for blood donations.
The United States said Thursday there had been "serious violations of the cease-fire by both sides" and warned it would only be ready to mediate between the warring parties when they get "serious".
"Once the forces make clear by their actions that they are serious about complying with the cease-fire, the United States and the Kingdom of Saudi Arabia are prepared to resume facilitation of the suspended discussions to find a negotiated solution to this conflict," a State Department spokesperson said.
In both north and south Khartoum on Wednesday, troops loyal to army chief Abdel Fattah al-Burhan attacked key bases of the RSF led by commander Mohamed Hamdan Daglo, residents told AFP.
One witness said there was "heavy artillery fire from army camps" in the capital's north.
Another reported "artillery blasts on the RSF camp in Al-Salha" in southern Khartoum – the largest paramilitary base and arsenal in the city.
The attacks came two days after U.S. and Saudi mediators said the two sides had agreed to extend by five days the initial week-long humanitarian truce.
Mediators admitted the truce had been "imperfectly observed", but said the extension would "permit further humanitarian efforts".
The army walked out "because the rebels have never implemented a single one of the provisions of a short-term cease-fire which required their withdrawal from hospitals and residential buildings", a Sudanese government official said.
Despite repeated pledges from both sides, fighting has flared this week both in greater Khartoum and in the western region of Darfur.
"The army is ready to fight until victory," Burhan declared during a visit to troops in the capital.
The RSF said they would "exercise their right to defend themselves" and accused the army of violating the truce.
Since fighting erupted on April 15, more than 1,800 people have been killed, according to the Armed Conflict Location and Event Data Project.
The U.N. says 1.2 million people have been internally displaced and more than 425,000 have fled abroad.
Yaqout Abderrahim escaped Khartoum for Port Sudan, where she has been waiting 15 days for a rare seat on a flight out.
"We want to leave at any price because our houses are destroyed and we no longer have any means to raise our children," she told AFP.
More than half the population – 25 million people – are now in need of aid and protection, the U.N. says.
Entire districts of Khartoum no longer have running water, electricity is only available for a few hours a week, and three-quarters of hospitals in combat zones are not functioning.
Hundreds have been killed in Darfur, on Sudan's western border with Chad, the United Nations said.
Darfur has never recovered from the years-long war that began in 2003 when a rebel uprising led strongman Omar al-Bashir to unleash the Janjaweed militia, from which the RSF are descended.
Experts say Burhan is facing increasing pressure from his own Islamist supporters and remnants of the Bashir regime, with whom he had built a symbiotic relationship in order to gain power.
