Sudan’s Rapid Support Forces (RSF) were accused on Sunday of carrying out summary executions of civilians in the besieged North Darfur city of El Fasher, with videos circulating online that appeared to show the killings.

The accusations come as the RSF intensifies shelling and ground assaults in an attempt to capture El Fasher, the Sudanese army’s last stronghold in the vast Darfur region.

Local sources told Sudan Tribune that RSF fighters shot dead 12 unarmed young men in the Shaqra area, about 13 km (8 miles) west of the city, claiming they were smuggling goods.

A separate artillery attack by the RSF on Saturday killed at least 30 people in El Fasher’s neighbourhoods and the sprawling Abu Shouk camp for displaced people, according to a statement from the El Fasher Resistance Committees. The committees also accused RSF fighters of infiltrating the camp, executing residents, and taking others to unknown locations.

One widely-circulated video appeared to show an RSF soldier questioning a restaurant owner, Ahmed Qandoul, about his tribe and the location of an army commander before shooting him dead at close range. Reuters could not independently verify the footage.

The Darfur Youth Authority’s Human Rights Observatory, a local monitoring group, called the incident a war crime and part of a “systematic policy targeting civilians.”

The RSF stated that it had launched an investigation to determine if the assailant in the video belonged to its forces, adding that he would be held accountable if found to be a member of its forces.

The escalating violence has triggered a new wave of displacement from the city’s northern neighbourhoods toward its centre, residents said. They added that RSF fighters also destroyed a major water source in the Abu Shouk area, cutting off drinking water for a large number of citizens.

The United Nations has said it is investigating reports of other field executions by the RSF after its forces briefly penetrated the camp last week before being repelled by the army.