Ritscher succeeds Karim Asad Ahmad Khan of Britain, who was sworn in as prosecutor of the International Criminal Court in June.

The UN team aims to support the government of Iraq in its indictment of IS members by collecting, preserving and storing evidence that may amount to war crimes, crimes against humanity and genocide.

In May, the team said it had gathered clear and convincing evidence that IS had committed genocide against members of Iraq's Yazidi minority.

Ritscher previously served as a federal public prosecutor in Germany and has more than 30 years' experience in international and domestic criminal prosecutions, the UN said in a statement announcing his appointment.