The newspaper states that the Austrian intelligence services have been taping suspects' telephones for around two years. The alleged leader of the group is a father of five from Bosnia, considered to be the "mouthpiece" of the European branch of IS, recruiting Islamists.
Islamic State jihadist group, also known as ISIS or ISIL, has declared a caliphate in areas of Syria and Iraq that were seized in the summer. IS, notorious for documented human rights abuses, came to prominence in 2012 fighting Syrian government forces.
Residents from Britain, France, Sweden, Germany and other countries have traveled to the war-torn region acting as mercenaries in the jihadist militia. Those returning home are closely monitored by local intelligence services.
The US State Department said in August that some 12,000 would-be mercenaries from more than 50 countries have joined IS in the Middle East, drawn by propaganda targeted largely at youth.
