The army had been criticised for leaving the capital of Gezira state, without putting up a fight.
More than 300,000 people have fled Gezira, which had been seen as a safe haven in the eight-month civil war.
Four days after Wad Madani’s fall, Gen Abdel Fattah al-Burhan addressed the matter publicly.
“We will hold every negligent commander accountable. Those who were responsible for this withdrawal will also be held accountable without leniency,” he said.
The army says it will investigate the “surprise withdrawal”, which enabled the paramilitary Rapid Support Forces (RSF) to take control of Wad Madani.
The RSF announced that they have captured the entire Gezira state but the BBC has been unable to verify this. However, aid workers have been pulling out of neighbouring areas in case the fighting continues to spread.
The RSF, who have been battling the army since April, are believed to control nearly 70% of Sudan’s capital city, Khartoum, along with most of the western Darfur region.
Hundreds and thousands of people have fled from unsafe areas, like Khartoum, to Gezira and Wad Madani.
Islamic Relief Sudan Director Elsadig Elnour was in Wad Madani when fighting broke out, and told BBC Newsday that civilians there were “panicked”.
Of Wad Madani’s large population of displaced people, Mr Elnour said: “Already they’re not recovered from the trauma they had in Khartoum and again they’ve started to move to other places in Sudan.
“They don’t know where to settle and who will provide assistance to them.”
Along with housing displaced people, Wad Madani also replaced Khartoum as a hub for aid operations when the conflict began.
Since the RSF took control of the city, many of these aid groups have left for other regions.
Staff at medical charity EMERGENCY NGO are among those who fled Wad Madani, with Programme Coordinator Dr Gina Portella calling the situation a “disaster”.
Her team has struggled to monitor the whereabouts and welfare of their patients in Wad Madani due to poor telecommunications in the city.
“We hope in a few days we will be able to understand where they are,” she said.
One resident who refused to flee told the BBC: “Wad Madani is a ghost town.”
“The shops are closed, hospitals are out of service and there is no presence of the army or the police. Only the RSF fighters are here,” said a college professor, who asked not to be named.
Many civilians and aid workers who fled Wad Madani have now moved to Gedaref, Sennar and White Nile states.
There is growing unease that the RFS may now attempt to capture Gedaref, east of Gezira.
In light of these concerns, Mr Elnour says he has prepared to move his Islamic Relief staff from Gedaref.
“Everyone is panicking – even in other cities than Gedaref – that the RSF will escalate the war and reach Gedaref,” he said.
The war has forced around seven million people from their homes, the United Nations says.
Stephane Dujarric, spokesman for the UN’s secretary-general, said Sudan was experiencing the world’s largest displacement crisis.
Before the war began, the RSF and the army had shared power with civilians after the overthrow of former strongman Omar al-Bashir. The two factions then staged a coup together in 2021.
War between the two sides erupted this year following a disagreement over an internationally backed political transition plan.
As well as displacing millions, the conflict has left Khartoum in ruins, caused a humanitarian crisis and triggered ethnically driven killings in Darfur.
Source : BBC news