Sudan's paramilitary Rapid Support Forces said on Sunday it had seized full control of El-Fasher, the last major urban centre in western Darfur still outside its hands.

The announcement came just hours after the RSF claimed it had captured the army's main base in the city, which it has besieged since May 2024.

In a statement, the group said it had "extended control over the city of El-Fasher from the grip of mercenaries and militias," referring to the Sudanese army, which it has been fighting since April 2023.

The claim could not be independently verified, and the army and its allies have yet to comment.

Access to the region remains extremely limited due to intense fighting.

The United Nations has called for safe passage for "trapped and terrified" civilians in El-Fasher.

UN aid chief Tom Fletcher said he was deeply alarmed by reports of civilian casualties and forced displacement in fighting in the city.

"With fighters pushing further into the city and escape routes cut off, hundreds of thousands of civilians are trapped and terrified – shelled, starving, and without access to food, healthcare, or safety," Fletcher said in a statement.

"Civilians must be allowed safe passage and be able to access aid," he added.

"Those fleeing to safer areas must be allowed to do so safely and in dignity."

Those who did stay, including local responders, had to be protected, while attacks on civilians, hospitals and humanitarian operations "must stop immediately", he said.

Around 260,000 civilians, half of them children, remain trapped in El-Fasher without aid or food.

"Safe, rapid, and unimpeded humanitarian access must be allowed to reach all civilians in need," said Fletcher.

"We have lifesaving supplies ready, but intensified attacks have made it impossible for us to get aid in," he added.

He called for an immediate ceasefire in El-Fasher, across Darfur and throughout Sudan, and said those responsible for violations of international humanitarian and human rights law had to be held to account.

Local pro-army fighters, the Popular Resistance, have accused the RSF of running a "media disinformation campaign" to weaken morale, insisting residents were still "resisting in the face of terrorist militias."

The local resistance committee, a pro-democracy group, said the targeted infantry division, the Sixth Division, was "just empty buildings," with the army now based in "more fortified positions."

Since August, the RSF has intensified artillery and drone attacks on El-Fasher, eroding the army's last defensive lines after about 18 months of siege.

RSF videos on Sunday appeared to show fighters celebrating beside a sign marked "Sixth Infantry Division," while footage from across Darfur purportedly showed crowds celebrating alongside RSF fighters.

If confirmed, the capture of the city would mark a major turning point in Sudan's two-year war, which has killed tens of thousands and displaced nearly 12 million people.

It would bring all five Darfur state capitals under RSF control, consolidating its recently established parallel administration in Nyala. (AFP)