Police in Vienna detained the teen on Saturday after her family in Sweden managed to track her on her mobile and alert authorities. Austrian police have until Monday to decide whether to charge the girl with a crime, release her or send her back to Sweden.
The newspaper writes that the girl was on an international wanted list since Wednesday, and that Swedish police are working on the case.
"We are aware of and working on the case," Stefan Ray, of the Swedish police's National Operational Department, told Radio Sweden.
Swedish Radio's local channel in Östergötaland reports that Linköping's social services has been alerted to the case, as well, and that the teen would be taken into care if she is returned home.
"When she comes back to Sweden, we will investigate her needs and what we should do," Anita Lådö at Linköping's social services told the station.
The girl's family told Expressen that the teenager recently became radicalized and is said to have talked positively about IS in different contexts.
The girl was born and raised in Sweden and attends high school.