The man was arrested on the Czech-German border on the back of an international arrest warrant issued by Croatia. He now faces being remanded in a Croatian jail.
The Swedish Foreign Ministry says that Swedish consular officials in Germany have been in touch with the man and that they are "supporting him in the way that Swedish citizens are normally supported."
"The extradition question is now a matter for Croatia and Germany. The matter will by tried under German law," said Foreign Ministry spokesman Marcus Oscarsson.
Local media in Jämtland, northern Sweden, where the man lives, say that he is a Croatian Serb who came to Sweden from Croatia as a refugee early in the 1990s. Prior to that he had been accused of a robbery in Croatia in 1991. He had told his party colleagues that he was tortured in jail.
The man had been found not guilty in the court of first instance, but the case was taken up by a higher court, where he was reportedly convicted. By that time he was already living in Sweden.
According to reports, negotiations between Germany and Croatia to extradite the man have already started.