Citing German federal prosecutors, news agency TT reports that the man is a member of the Kurdistan Workers' Party (PKK), which is listed by the EU as a terrorist organization.
Prosecutor Ronnie Jacobsson told Swedish Radio P4 Stockholm that there was a European arrest warrant out for the man, who is suspected of committing terrorist crime a couple of years ago.
Jacobsson says that as far as he understands, based on the documents he's received, the arrest has nothing to do with Sweden, but with something that happened in Germany a couple of years ago.
The man, who was born in 1980, was arrested at eight-thirty this morning after being stopped at a passport check. The arrest is reported to have proceeded calmly. According to Aftonbladet, the man was on his way to Turkey.
"I have not heard anything other than that he was travelling alone," Jacobsson told TT. Jacobsson also said that the man is not a Swedish citizen. Jacobsson said that Säpo, the Swedish security service, has taken over the case and will be holding a hearing with the man. The courts will decide whether to extradite the man to Germany.
Fredrik Milder, Säpo's press secretary, said to TT that he could only confirm that a request for international legal help had come in to the national unit for security cases.
"We have knowledge of the case. I can't go into what measures have been taken," Milder said.