Thirteen people were injured in Vienna when approximately 1,000 left-wing activists stopped a demonstration attended by an equal number of extreme right-wing sympathizers on Saturday, police reported.
Police said its officers used pepper spray after left-wing protesters began throwing rocks, bottles and iron rods at members of the xenophobic Identitarian movement.
One person was reported to prosecutors for alleged neo-Nazi propaganda, while seven counter-demonstrators were detained.
Four officers were among the injured.
In recent years, anti-refugee and xenophobic tendencies have increased in many European cities, causing clashes between pro-refugee activists and the far-right groups.
Austria, a country of 8.5 million, has mostly served as a conduit into Germany for refugees and migrants from the Middle East and Africa. After initially welcoming refugees, the Austrian government capped the number of asylum claims it would accept this year at 37,500, and it has made family reunification harder for migrants.
In late May, Van der Bellen, a Greens politician running as an independent, narrowly won the presidential election in Austria, but concerns are still high as far-right leader Hofer reflected the major political surge amid the general trend for far-right candidates across Europe
Far-right parties are gaining strength and being voted into power in many European countries. Their typical hot button issues include keeping out refugees and skepticism toward the EU. Recently, support for far-right, anti-immigrant and Eurosceptic parties has surged in Serbia, the United Kingdom, Denmark, Finland, France, Hungary and the Netherlands.