The possibility of staving off an escalation of fighting in the Sudanese city of El-Obeid is quickly fading, a top UN official warned Friday, adding that the increasing use of drones was making the conflict "more unpredictable."

The city, a strategic hub in the southern Kordofan region, has been encircled for months by the Rapid Support Forces, the paramilitary group that has been fighting Sudan's army since April 2023.

For a week, the United Nations, several governments and non-governmental organizations have warned of a possible imminent paramilitary offensive, similar to the brutal seizure of El-Fasher in Darfur last year.

"Over the past two weeks, drone attacks by both parties in the area have increased significantly, while the Rapid Support Forces have expanded their presence around the city," UN undersecretary for political affairs Rosemary DiCarlo said.

"The window to avert a wider escalation in El-Obeid is rapidly narrowing," she told the Security Council.

UNICEF's deputy executive director Hannan Suleiman said while the fighting was intensifying, "an estimated 500,000 civilians are at risk."

"Children are at an immediate and growing danger of being killed, injured, displaced, or exposed to other grave violations," Suleiman said, pointedly adding: "The children of Sudan cannot survive on expressions of concern."

The two UN officials and several Security Council members expressed concern about the increasing use of drones in the conflict.

For DiCarlo, it is "making the conflict more unpredictable, more geographically dispersed and more lethal for civilians" -- and could potentially eliminate the drop in fighting traditionally seen during the rainy season.

DiCarlo called for "all external actors to use their influence to help end this war, rather than be complicit in it," adding: "Let me be clear. There are clear warning signs of worse things to come if we don't act."

The conflict in Sudan has killed tens of thousands of people and forced more than 11 million from their homes, creating what the UN describes as the world's largest displacement and hunger crises.