The cause of the blast, which resounded across the capital, was not immediately clear.

Khartoum has seen relative calm since the army, which has been locked in conflict with the paramilitary Rapid Support Forces (RSF) since April 2023, regained control of the capital last year.

An AFP journalist in Omdurman, Khartoum's twin city just across the Nile, reported hearing one blast from the direction of central Khartoum.

A witness in the city centre also described a "single, loud explosion" but said there were no immediate signs of "fire or rising smoke".

Other residents across the capital confirmed hearing the blast.

There was no immediate statement from authorities on what caused the explosion.

In the months following the army's recapture of the capital last March, the RSF launched drone strikes at military bases and civilian infrastructure in the capital. But there have been none in recent months, and the city has regained a sense of normality, with 1.7 million displaced people returning.

Outside Khartoum, drone attacks by both the army and the RSF have continued to disrupt daily life, with some strikes killing dozens at once.

This week, the United Nations said that drone strikes had killed more than 500 civilians between January and mid-March, pointing to "the devastating impact of high-tech and relatively cheap weapons in populated areas".

The wider conflict, now approaching its three-year mark, has killed tens of thousands of people, forced more than 11 million from their homes and created what the UN describes as the world's largest displacement and hunger crises.