The UN envoy to Sudan, Volker Perthes, has announced that he's resigning.

He told the UN Security Council that the Sudan conflict which erupted between rival military factions in April risked becoming a full-blown civil war.

It comes more than three months after Sudan declared him unwelcome after the war erupted.

Five million people have been displaced in the clashes between the Sudanese armed forces and the rival paramilitary forces, the Rapid Support Forces (RSF).

In his final speech to the Security Council, Mr Perthes was extremely critical of Sudan's military ruler, Gen Abdel Fattah al-Burhan and the RSF chief Gen Mohamed Hamdan Dagalo better known as Hemedti.

Mr Perthes said the two leaders chose to plunge the country into a war that is leaving a tragic legacy of human rights abuses. He blamed the RSF for the sexual violence, looting and killings in areas it controls.

He also condemned the Sudanese armed forces for the indiscriminate aerial bombings.

As he was speaking medics in the city of Nyala in Darfur were dealing with the aftermath of yet another atrocity. Forty people died there in air strikes, adding to the more than 50 people who were killed on Sunday.

The RSF fighters are embedded in densely populated urban areas and the Sudanese military appears to view these areas as legitimate targets.