Air strikes by the Sudanese army have killed at least 23 people and injured more than 40 people south of the capital Khartoum.
Saturday’s airstrikes targeted the main camp held by the paramilitary Rapid Support Forces in southern Khartoum, hitting the central market and nearby residential areas.
Victims include businessmen, shoppers and local residents.
Forces Without Borders has been fighting an 18-month civil war with the army that has claimed up to 150,000 lives and displaced a fifth of Sudan’s population, according to United Nations estimates.
The injured are being treated in hospital, according to a spokesman Nobel Prize-nominated rescue network, emergency response room.
Emergency workers reported that hospitals were overwhelmed by the number of injured.
Fierce fighting has escalated since Friday around Khartoum, largely controlled by Forces Without Borders, with the military stepping up airstrikes in the city center and southern areas.
Witnesses said troops were advancing toward Khartoum from nearby Omdurman, where clashes broke out on Saturday.
Earlier this week, the Sudanese government presented what it called new evidence to the United Nations Security Council that the United Arab Emirates was arming and supporting Forces Without Borders and called for action against the Gulf state.
The UAE has long denied supporting Forces Without Borders.
Both Doctors Without Borders and the Sudanese Armed Forces have been accused of atrocities.
“Relentless hostilities across the country are causing suffering for millions of civilians, triggering the world’s fastest-growing displacement crisis,” the United Nations warned last month.
The report says Sudan now has “the world’s largest hunger crisis”.
Additional reporting by Natasha Booty and BBC Monitoring
