The Sudanese Armed Forces and the rival Rapid Support Forces both confirmed prolongation of a truce that was due to end at midnight (2200 GMT), with the army saying the extension came due to "U.S. and Saudi (Arabia) mediation."
The army said that although the rebels had intended to try to attack some sites it hoped that they would abide by the cease-fire.
Witnesses on Sunday evening reported continued armed clashes as well as fighter jets soaring above various parts of the capital and its twin city Omdurman, across the Nile River.
The civil aviation authority on Sunday announced Sudan's airspace would remain closed until May 13, with the exception of aid and evacuation flights.
"There has been very heavy fighting and loud gunfire," a southern Khartoum resident told AFP earlier in the day.
Sudan's former prime minister Abdalla Hamdok warned Saturday against the conflict's deteriorating into one of the world's worst civil wars.
"God forbid if Sudan is to reach a point of civil war proper... Syria, Yemen, Libya will be a small play," Hamdok told an event in Nairobi. "I think it would be a nightmare for the world."
The United Nations' World Food Program (WFP) has warned the unrest could plunge millions more into hunger in a country where 15 million people already needed aid to stave off famine.
More than 500 people have been killed, thousands injured and tens of thousands of people forced to leave their homes for safer locations within the country or abroad since battles erupted on April 15.
Information for this report came from Reuters and Agence France-Presse.