Austrian police have detained a 17-year-old Swedish girl who said she was on her way to Syria and is suspected of planning to join Islamist militants there, a Vienna police spokesman said on Sunday.

The parents of the girl, who has no previous link with Syria, had informed Swedish police of their daughter's travel plans and their concerns about the possibility of her joining Islamic State militants.

A description of the teenager allowed Austrian police to identify and detain her at a Vienna train station on Saturday. Austrian police had no information on Sunday about whether the girl had converted to Islam or grown up in that faith.

"She said she wanted to go to Syria and wanted to meet a friend in Vienna. She did not specifically mention Islamic State (militants), but the suspicion would not be far-fetched," the spokesman said.

He added that there was no evidence that the girl had planned any activity in Austria. Austrian authorities can detain her until Monday to decide whether to release her, raise terrorism-related charges or send her back to her parents in Sweden, he said.

In May, an Austrian court sentenced a 14-year-old boy who downloaded bomb-making plans onto his Playstation games console to a two-year jail term after he pleaded guilty to terrorism charges.