VIENNA : Authorities suspect around 130 people resident in Austria - most of them foreign nationals - have allied themselves with militants fighting abroad, officials in Vienna said on Friday, raising their estimate by nearly a third.
Public safety director Konrad Kogler told a news conference the 130 figure included "people actively participating in combat as well as ones who have returned to Austria, because both groups of people are relevant for us".
He thought around two-thirds of them had come back to Austria and one-third were in battle or on the way there.
Officials were tracking the target group's foreign travel and monitoring their activities when they return given the security risk they might pose, he said.
He said 40 of the 130 were Austrian citizens. The others were primarily from Russia, the Balkans and Turkey.
Austria has a population of around 8.5 million people.
The subject is at the top of the news agenda in the neutral Alpine republic after police arrested nine people this week who prosecutors said were believed to be on their way to Syria to join the fighting.
They have not given any more details about the suspects' destination or said what forces they might have joined.
Militants are among the rebel forces fighting Syrian President Bashar al-Assad's government in a civil war that the United Nations says has cost more than 190,000 lives.
The insurgency is split between competing factions in Syria, with the militant Islamic State emerging as the most powerful. The group also controls large parts of Iraq.
Kogler did not confirm reports that the nine suspects - one aged just 17 - were Chechens, but said many were Russian citizens.
The suspects had mostly come to Austria as young people and got political asylum that could be revoked should they be convicted of joining a terrorist organisation, officials said.
All nine have been remanded to investigative custody.
Interior Minister Johanna Mikl-Leitner said support for radical Islamists was on the rise in Austria and called for closer European cooperation to address the issue.
"We need to close ranks across Europe in the fight against terrorism and jihadism," she said, urging a policy of zero tolerance.
Roughly half a million Muslims live in Austria, representing about 6 percent of the total population.
Several people have been arrested in Europe in recent months amid fears that fighters returning from Syria could stage attacks on European soil. Authorities in Graz detained a cleric in June on suspicions he was radicalising Muslims and recruiting them to fight in Syria.