Dhaka, Nov. 2 -- Survivors and aid agencies have reported widespread killings, abuse and disappearances after the paramilitary Rapid Support Forces (RSF) seized el-Fasher, the capital of Sudan's North Darfur state, raising fears of a new humanitarian catastrophe.

El-Fasher, the last stronghold of the Sudanese army in Darfur, fell to the RSF on Sunday after an 18-month siege. Since then, the United Nations and international aid organisations have warned of mass killings, rape, and other atrocities.

Alkheir Ismail, a young man who fled to Tawila, about 50 km from el-Fasher, recounted how RSF fighters stopped a group of 300 people as they tried to escape. Only he survived after being recognised by one of the captors. "There was a young man...