The source, who spoke on condition of anonymity because they were not authorised to brief the media, said RSF drones "targeted the headquarters of the army's 17th Infantry Division in Sinja, the capital of Sennar state".

Since April 2023, the civil war between the army and the RSF has killed tens of thousands and left around 11 million people displaced internally and across borders.

Sennar state has seen relative calm since the army recaptured key Sudanese cities in late 2024 in an offensive that later saw it regain the capital Khartoum.

The Sennar region was last targeted by drones in October.

One resident of Sinja told AFP on Monday that they "heard explosions and anti-aircraft fire".

Sinja, which is located around 300 kilometres (180 miles) southeast of Khartoum, lies on a road linking army-controlled areas of eastern and central Sudan.

The strike comes a day after the army-aligned government said it had returned to Khartoum following three years operating from its eastern wartime capital of Port Sudan.