An extensive earthen wall is being built around the besieged Sudanese city of el-Fasher and is intended to trap people inside, according to research from Yale University.
From satellite images, the university's Humanitarian Research Lab (HRL) has identified more than 31km (19 miles) of berms - or raised banks - constructed since May in territory outside the city occupied by the paramilitary Rapid Support Forces (RSF).
El-Fasher, under siege for more than a year, is the last major foothold in Darfur for Sudan's army, which has been battling the RSF since April 2023.
The Sudan Doctors Network has told the BBC that the RSF was intensifying its offensive there and deliberately targeting civilians.
Yesterday there was a shelling in a civilian area down in the city centre that ended up killing almost 24 civilians and injuring 55 people, among them five women, Dr Mohamed Faisal Hassan, from the medics association, told the BBC's Newsday programme.
The attacks on the central market and a residential area were deliberate and heinous, he said.
Both sides in the conflict have been using berms as a defensive tool, but the RSF's construction of the walls is described by Yale's HRL as creating a literal kill box around el-Fasher.
Humanitarian groups have faced severe limitations in accessing el-Fasher, resulting in dire shortages of food, medical supplies, and essential goods for about 300,000 trapped residents. Civilians attempting to flee face threats of violence from RSF forces.
Dr Hassan narrated how, Some civilians are trying to escape the city but sadly they are being targeted and killed by the RSF forces. The humanitarian crisis escalates as observers predict that the complete fall of el-Fasher could lead to a partitioning of Sudan under warring factions.
