The UN and African blocs have warned of the "ethnic dimension" to the conflict in western region of Darfur in Sudan.
Government troops are locked in conflict with RSF forces and allied militias.
The fighting is concentrated mainly in Darfur and the capital Khartoum, also in Blue Nile state near Ethiopia, as well as in South Kordofan state.
On Monday leaders of Ethiopia, Kenya, Somalia and South Sudan -- IGAD members handling the Sudan file -- are to meet in Addis Ababa to discuss a way out of the crisis.
Sudan's army chief Abdel Fattah al-Burhan and RSF commander Mohamed Hamdan Daglo have been invited but neither side has confirmed they will attend.
The conflict in Sudan has already created 2.2 million internal refugees.
Numerous ceasefires have been announced but repeatedly ignored.