Former president Thabo Mbeki has called for an urgent ceasefire in Sudan and an immediate return to negotiations that will usher in a civilian government.

In a statement issued through the Thabo Mbeki Foundation on Tuesday, he said only those two measures "will address the current expectations of the long-suffering people of Sudan".

On Saturday, Sudan was plunged into chaos when the national army and the paramilitary Rapid Support Forces (RSF) clashed.

The army is loyal to Sudan's de facto leader, General Abdel Fatah al-Burhan, while General Mohamed Hamdan Dagalo leads the RSF.

The UN estimated at least 185 civilians have been killed and 1 800 injured since the fighting broke out.

Mbeki has in the past worked with the people of Sudan, particularly as the chairperson of the African Union High Implementation Panel (AUHIP).

He engaged former president Omar al Bashir on several occasions.

Al Bashir was later overthrown during the army and civilian-supported coup of 2019.

As AUHIP chairperson, Mbeki pushed for the cessation of hostilities and a ceasefire in Sudan's fractured socio-political fabric.

The country now finds itself in a similar situation.

Mbeki's observations and comments will carry added weight as many of the problems he encountered remain to this day.

In addition, the fall of Al Bashir, which brought the military into civilian politics, has not been properly addressed.

In that regard, Mbeki said the ongoing fighting would further affect the chances of a civilian-led solution to the country's legacy of problems that span from the socio-economic to political sphere.

"[I]n the midst of a serious economic crisis, great damage is being caused to civilian, economic and other infrastructure it will be difficult to replace," he added.

"Sudan will not be able to achieve stability and gain the ability to successfully address its deeply entrenched socio-economic challenges unless it completes the transition to democracy following the overthrow of the Bashir regime."

The Intergovernmental Authority on Development said Djibouti President Omar Guelleh, Kenya President William Ruto, and South Sudan President Salva Kiir were due to travel to Khartoum to broker a peace deal.