Deso Dogg
Germany's most prominent jihadi operating in Syria and Iraq, Denis Cuspert, otherwise known as 'Deso Dogg'.Twitter / @APHClarkson

Former rapper and Isis militant Deso Dogg could face prosecution for war crimes by German authorities.

German authorities will push for war crimes charges against citizens suspected of committing atrocities for Isis in Iraq and Syria, Welt am Sonntag reported, citing security officials.

Prosecutors in Karlsruhe investigating the activities of 83 German nationals suspected of fighting for Isis said that among those who authorities were preparing to charge were Denis Cuspert, 39, also known as "Deso Dogg", a former rapper from Berlin, and German-Algerian Fared S, 25, from Bonn.

Cuspert, who goes by the nome de guerre Abu Talha al Almani, appeared in an Isis propaganda film last year holding aloft a severed head.

Fared S, who German law prevents from being fully named, appeared in a propaganda video last year sitting on top of a heap of corpses, which he claimed belonged to Syrian army soldiers.

"There is every indication that IS fighters commit crimes," the Cologne-based international law expert Claus Kreß told the newspaper, "namely crimes against humanity, war crimes in a non-international armed conflict – and perhaps even genocide."

If caught and found guilty, both face life sentences.

German authorities believe that as many as 600 nationals may have travelled to Iraq and Syria to fight in the country's civil war.