Berlin: German authorities say they have arrested a 31-year-old Iraqi man on suspicion of membership in a terrorist organisation and war crimes as part of the Islamic State group.

Federal prosecutors said today the man, identified only as Raad Riyadh A A in line with privacy laws, was apprehended in Berlin yesterday.

They allege he joined IS in Mosul in June 2014 and participated in the killing of two Shiite Muslims. Four months later they say he was involved in the execution of a captured Iraqi military officer.

He is also accused of extorting money from businesses to support IS.

After arriving in Germany in July 2015, prosecutors say, he tried to recruit two other Iraqis and convince a third to carry out a suicide attack.