Austrian police on Monday raided more than 60 addresses allegedly linked to radical Islamists, with orders for 30 suspects to be questioned, prosecutors said.
The operation came a week after a convicted Islamic State group supporter killed four people in a shooting rampage in the heart of Vienna, but prosecutors said the raids were not linked to the attack.
Interior Minister Karl Nehammer said the police action was aimed at "cutting off the roots of political Islam."
The Styria region prosecutors' office said it was "carrying out investigations against more than 70 suspects and against several associations which are suspected of belonging to and supporting the terrorist Muslim Brotherhood and Hamas organisations."
It said "the operation has no connection to the terror attack in Vienna of November 2" but was the result of "intensive and comprehensive investigations carried out for more than a year."
Among the alleged offences are forming a terrorist association, financing of terrorism and money laundering.
The raids took place in the Styria, Carinthia, Lower Austria and Vienna regions.