“I think she will be deported back to Sweden,” Ongun Burak Guzel told the Expressen daily.
The journalist is reported to have spent the evening in the Vatan police station and it remained unclear on Sunday what offence she is alleged to have committed.
“The police thought she was a demonstrator, that is why she was arrested,” Ongun Burak Guzel.
Neither the Foreign Ministry or the Consulate General of Sweden in Istanbul had on Saturday evening been approached by the Turkish authorities informing them of the matter.
“We have received information through the media, and the Consulate General in place have been contacted by the Turkish media and is following the case,” said Joakim Edvardsson Reimar at the Foreign Ministry’s press service.
“We don’t know anything more than that,” he added.
Taksim Square in central Istanbul has been the scene of demonstrations and disturbance for the past few weeks in the wake of a police crack down against a peaceful environmental sit-in in a nearby park.
Thousands returned to the square on Saturday evening to demand justice for a demonstrator who was killed by police fire.