The man was arrested by border police at around 7.30am when attempting to leave Sweden.
There is an international Interpol warrant for his arrest over terror-related activities in Russia, according to the Swedish prosecutor handling the case, who said the offences are not recent.
“He turned out to be wanted by Russia. He has been arrested while we try to figure out what exactly it is he is suspected of,” Ronnie Jacobsson told the TT news agency.
The 35-year-old is understood to be a Russian citizen, but also holds other passports. He was released from custody after questioning, the prosecutor announced late on Friday afternoon.
“My decision is based on what has been said during interrogations and what has emerged about the man. My overall assessment is that there are no grounds for continued detention,” said Jacobsson in a press release.
Earlier in the day he declined to confirm if Swedish authorities had contacted their Russian counterparts, nor would he disclose to which country the suspect was travelling.