Images posted on Twitter appeared to show a pig’s head impaled on scaffolding.
Police spokesman Patrick Maierhofer confirmed that the images were authentic and said they were taken "in the Islamic centre in Florian-Hedorfer street. We are investigating and have referred the case to the Federal Office for the Protection of the Constitution."
It’s not known who left the pig’s head at the centre, but even if someone confesses there is little the police can do as nothing was damaged and therefore there are no criminal charges.
The Islamic Federation could make a complaint within civil jurisdiction. Muslims are forbidden from eating pork or touching pig carcasses, as they are considered unclean.
The planned school has been unpopular in Austria, with Foreign and Integration Minister Sebastian Kurz saying the idea “is completely the wrong approach".