Sudan's paramilitary Rapid Support Forces (RSF) says it has taken control of the western city of el-Fasher, marking a turning point in the civil war.

The group said in a statement on social media that it had seized el-Fasher "from the grip of mercenaries and militias allied with the terrorist army".

The loss would be a huge blow to the Sudanese army as el-Fasher is its last remaining foothold in the Darfur region, leaving the RSF effectively in control of the area. The army has yet to comment.

It comes after the rebel group announced the capture of the army's 6th Division Headquarters, saying that it had destroyed "huge military vehicles" and taken military equipment.

BBC Verify has confirmed the authenticity of videos circulating on social media that show RSF fighters inside the army base.

Local pro-army fighters, the Popular Resistance, accused the RSF of running a "media disinformation campaign" to undermine the "high morale of the forces".

The RSF has surrounded el-Fasher for the last 18 months, with army positions and civilians under frequent bombardment. An estimated 300,000 people have been trapped by the fighting.

In August, satellite imagery showed a series of extensive earthen walls being constructed around the city, aimed at trapping people inside.

The RSF have been steadily advancing towards the 6th Infantry Division command - widely regarded as the army headquarters in the city - from several directions for weeks.

There are still some parts of el-Fasher under the control of the army and allied armed groups - but those are not expected to hold out for long now.

UN Relief Chief Tom Fletcher said on Sunday that he was "deeply alarmed" by the reports from el-Fasher, and called for an immediate ceasefire across Darfur and the rest of Sudan.

"Hundreds of thousands of civilians are trapped and terrified - shelled, starving, and without access to food, healthcare, or safety," Mr Fletcher said in a statement, adding that intensified attacks had made it "impossible" to get aid into the city.

Hunger and disease has spread across El-Fasher as residents contend with constant bombardment and dwindling food and medical supplies.

UN investigators have accused the RSF of committing numerous crimes against humanity during the siege. The US has said the RSF has committed genocide against Darfur's non-Arab population.

Sudan has been ravished by conflict since 2023, after top commanders of the RSF and Sudanese army fell out and a vicious power struggle ensued.

More than 150,000 people have died across the country and about 12 million have fled their homes, creating one of the worst humanitarian crises.

The army controls most of the north and the east, with el-Fasher being until now the last major urban centre in Darfur still held by government forces and its allies.

The RSF controls almost all of Darfur and much of the neighbouring Kordofan region.

The group has previously said that it hopes to form a rival government in al-Fasher when it assumes complete control.