Hamdok will form an independent cabinet of technocrats, and all political detainees will be released under an agreement between the military and civilian political parties, said Nasir, who attended the negotiations that led to the agreement.
The Sovereign Council will hold an urgent meeting on Sunday before announcing the agreement, said a source with knowledge of the talks.
It was unclear how much of the Forces of Freedom and Change civilian coalition that had been sharing power with the military would be part of the deal.
Activist groups leading protests since the coup have demanded that the military exit politics altogether.
The media adviser of military leader Abdel Fattah al-Burhan could not immediately be reached for comment.
Hamdok was placed under house arrest when the military seized power on Oct. 25, derailing a transition towards democracy agreed after the overthrow of long-ruling autocrat Omar al-Bashir in 2019.
The military dissolved Hamdok's cabinet and detained a number of civilians who held top positions under a power-sharing deal agreed with the military following Bashir's ouster.
Following the coup, Hamdok had demanded the release of all political detainees and a return to power-sharing as a precondition for negotiating, according to sources close to him.
The coup triggered a campaign of mass demonstrations against the military, and activists had called for further protests on Sunday.
Western powers that had backed Sudan's political transition condemned the takeover and suspended some economic assistance to Sudan.