The UN has called for safe passage for trapped civilians out of the Sudanese city of el-Fasher after paramilitary fighters announced they had seized control of the army's main base there.
Sudan's military has not acknowledged loss of the site, which would be a significant victory for the Rapid Support Forces (RSF) in the ongoing civil war.
UN chief António Guterres said the latest fighting marked a terrible escalation in the conflict, adding that the suffering of civilians was unbearable, AFP news agency reports.
El-Fasher is the last army foothold in the vast western region of Darfur, and has been besieged by the RSF and its allies for 18 months.
Heavy fighting has been reported since Saturday after RSF fighters captured the home of the North Darfur governor.
UN Human rights chief Volker Türk warned that the risk of further large-scale, ethnically motivated violations and atrocities in el-Fasher is mounting by the day. The Sudanese Doctors' Network stated that the RSF had already conducted ethnically motivated killings of dozens of people in the city and had looted medical facilities and pharmacies.
Imran Abdullah, an adviser to the RSF commander, denied the group's fighters were targeting civilians, claiming they aim to protect those fleeing conflict areas.
However, video evidence shows RSF combatants celebrating the capture of the army's el-Fasher headquarters. The RSF claims complete control of the city, although fighting reportedly continues in some areas.
With communication lines to el-Fasher largely cut off, those who have fled describe harrowing experiences filled with fear and uncertainty.
UN officials describe the situation as an epicentre of suffering as hundreds of thousands of civilians are trapped without access to food, healthcare, or safety.
The United States has echoed the UN's call for safe passage, attempting to negotiate a ceasefire as the civil war unfolds in Sudan, which has resulted in more than 150,000 casualties and over 12 million displaced individuals.
