0203 GMT July 20, 2019
Saturday's agreement would replace the existing 10-member military council that took power after the army ousted veteran leader Omar al-Bashir on April 11 amid massive protests, AFP reported.
"What happened yesterday is a step to have a civilian authority," said Mohamed Amin, one of thousands of demonstrators who have been camped for weeks outside headquarters.
The joint civilian-military council will be the overall ruling body, while a new transitional civilian government is expected to be formed to run the day to day affairs of the country, a key demand of protesters.
That civilian government will work towards having the first post-Bashir elections.
The demonstrators said they will pursue their sit-in until a civilian administration is set up.
"Last night's agreement is a step forward in the stability of our country. But I don't think we will leave the sit-in until we achieve our demand of a civilian government," said protester Sawsan Bashir.
Protest leader Ahmed al-Rabia confirmed to AFP the decision of forming a joint council.
"We are now in consultation about what percentage of the council should be represented by civilians and how much by the military," said Rabia, who is involved in talks.
Activists say the new council could be a 15-member body, with eight civilians and seven army generals.
The decision to have a joint council came after hours-long talks on Saturday, the first such by a joint committee representing the current ruling military leadership and protesters.
Bashir was ousted by the army after months of protests against his three-decade rule.
Thousands of demonstrators, braving volleys of tear gas fired by security forces, reached the sprawling military headquarters on April 6, demanding that the army support those opposing Bashir.
Five days later, the army toppled Bashir but then took power into its own hands through a 10-member transitional military council.
Protest leaders had previously held several rounds of inconclusive talks with the military council since Bashir was ousted.
The military council has so far insisted that it has assumed power for a two-year transitional period.
Western governments have expressed support for protesters' demands, but Sudan's key Persian Gulf Arab lenders have backed the military council, while African states have called for more time for the army to hand over to civilians.
As the joint committee met on Saturday, top opposition leader and former premier Sadiq al-Mahdi told reporters Sudan should "immediately" join the International Criminal Court.
The war in Darfur erupted in 2003 when ethnic minority rebels took up arms against Khartoum's Arab-dominated government, accusing it of social and political marginalization.
The United Nations says about 300,000 people have died in the conflict, with another 2.5 million displaced, many of them still living in miserable camps across the western region of the country.
Protest group spokesman Amjad Farid told reporters that Bashir and other official figures could be tried in Sudan.
Mahdi, who was forced from office by Bashir in a 1989 coup, said the army's ouster of Bashir was "not a military coup".
But he warned that Bashir cronies were still clinging on to power despite the upheaval.