Austria police raid dozens of 'Islamist-linked' targets
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.
"We are acting against these criminal, extremist and inhuman organisations with all our strength," Nehammer said in a statement.
The prosecutors' statement said the operation "was not targeted at Muslims or Islam as a religious community".
"On the contrary these measures are also intended to protect Muslims, whose religion is abused for the purposes of an ideology hostile to the constitution," it said.
Read also: Austria's Muslims wary of backlash after attack
Last Monday's shooting was the first major attack of its kind in Austria for decades and the first blamed on a jihadist.
The gunman was identified as Kujtim Fejzulai, 20, a dual Austrian-Macedonian national who was convicted last year of trying to go to Syria to join IS.
Austria has acknowledged security lapses in the run-up to the attack, including failing to act on warnings about Fejzulai and his contacts from Germany and Slovakia.
The head of Vienna's anti-terror agency was suspended last week after further revelations came to light about intelligence failings.
Last week the government also ordered the closure of two mosques in Vienna frequented by the attacker.
Meanwhile, European Council President Charles Michel and France's European Affairs Minister Clement Beaune will visit Vienna on Monday to meet Chancellor Sebastian Kurz and to discuss cross-border cooperation in the fight against terror.
Kurz will also take part in talks via video link with French President Emmanuel Macron, whose country faced growing criticism over offensive anti-Islam remarks as well as his defence of cartoons that insult the Prophet Muhammad.
Agencies contributed to this report.