Gadaref is the capital of al-Gadaref State that has remained under military control as the war between the regular army and the paramilitary Rapid Support Forces nears the one-year mark.

The RSF has taken control of the capital Khartoum, neighbouring Gezira state as well as most of the Darfur and Kordofan regions in the west, while the army holds the north and east of Sudan including its main Red Sea port.

Eyewitnesses said at least two drones had targeted military installations in Gadaref, which is located just to the east of Gezira, on Tuesday morning. They said they heard explosions as well as anti-aircraft missiles being fired from the ground.

Gadaref Governor Mohamed Abdelrahman Mahgoub confirmed the drone attack, without apportioning blame. He urged civilians who have joined a "popular resistance" movement to prepare to defend the region. Eyewitnesses said the army had deployed across Gadaref city as well.

Previous RSF takeovers of territory during the war have led to widespread looting, detentions and reports of rape, along with waves of displacement, according to eyewitnesses and human rights groups.

More than 8.5 million people have fled their homes since the war began, while aid groups warn of impending famine in many parts of the country, Africa's third largest by size.

Last week, a similar drone attack struck the army-controlled city of Atbara, north of Khartoum, during a gathering of an army-aligned militia. Neither the army or RSF made any statements acknowledging the attack.

RSF fighters have continued raids into villages across Gezira state, next to both Khartoum and Gadaref, while the army has said it has launched a large-scale operation, including airstrikes, to reverse gains by the paramilitaries.

The army, assisted by drones, has also made advances in the city of Omdurman, across the Nile River from the capital.