Reports from Sudan say fighting has broken out in all parts of the capital just before a three-day ceasefire expired early in the morning.
Witnesses say the Sudanese army and the rival Rapid Support Forces (RSF) clashed in Khartoum.
There are also reports of anti-aircraft fire during an army aircraft operation in Omdurman.
The latest truce had been brokered by Saudi Arabia and the US – as with previous ceasefires there were reports of violations on both sides.
Armed conflict between Sudan’s army and the paramilitary RSF began in April.