Opening an emergency session of the UN Human Rights Council in Geneva, Mr Türk urged countries "with influence in Africa" to help end the violence.

Fighting has been continuing in the capital, Khartoum, and in the city of Omdurman.

On Wednesday, witnesses in Khartoum reported air raids and counter-fire from anti-aircraft guns.

This is the fourth week of fighting between army chief Abdel Fattah al-Burhan and his former deputy Mohamed Hamdan Daglo, who commands the paramilitary Rapid Support Forces (RSF).