U.S. Secretary of State Antony Blinken held separate calls with the army chief and head of the paramilitary Rapid Response Forces (RSF), whose power struggle has killed close to 200 people and derailed an internationally-backed deal for a shift to civilian government after decades of autocracy and military rule.
Blinken, speaking from Japan, said he had telephoned both RSF leader General Mohamed Hamdan Dagalo, known as Hemedti, and Sudan's army chief General Abdel Fattah al-Burhan, appealing for a 24-hour ceasefire "to allow the Sudanese to be safely reunited with families" and to provide them with relief.
The secretary said a U.S. diplomatic convoy came under fire on Monday in an apparent attack by fighters associated with the RSF, adding that all those in the convoy were safe. He called the incident "reckless" and said any attacks or threats to U.S. diplomats were unacceptable.
Gunfire echoed across Sudan's capital for a fourth day on Tuesday, accompanied by the sound of warplanes and explosions, a Reuters reporter said. Residents in Khartoum's twin city of Omdurman, on the other side of the Nile, also reported air strikes that shook buildings and anti-aircraft fire.
The RSF's Hemedti, whose whereabouts have not been disclosed since fighting began, said he had "discussed pressing issues" with Blinken during their call and more talks were planned.
In posts on Twitter he said the RSF approved a 24-hour armistice. The RSF also issued a statement saying it was waging a continuing battle to restore "the rights of our people."
Both sides have offered truces in previous days, but the fighting has not stopped.
The clashes in Khartoum and its adjoining sister cities of Omdurman and Bahri are the worst in decades and risk tearing Sudan between two military factions that had shared power during a rocky political transition.
The army's media office said Burhan would pardon RSF officers and soldiers who surrender and "lay down their arms." Those that do would be absorbed into the armed forces, he said.
The eruption of fighting followed rising tensions over the RSF's integration into the military under a civilian transition plan.