Only hours earlier, Khamis Abbakar had accused both the RSF and allied militias of committing genocide against people from the Masalit ethnic group.
Mr Abbakar, who was killed in El Geneina, had warned that the attacks had spread across the city and called for international intervention.
The RSF has not commented on the allegation.
There has been similar violence in the cities of Nyala and Zalingei.
UN Secretary General Antonio Guterres has said he’s appalled by the escalating ethnic and sexual dimension of the violence against civilians in Darfur.
The region has seen periods of conflict since the early 2000s when millions were displaced and hundreds of thousands killed after Arab militias were deployed to fight non-Arab rebels.
