The arrest of the man at the Stockholm airport was linked to a dragnet launched in March which targeted PKK activities in Belgium, said Leen Nuyts, a spokesperson for the Belgian federal prosecutor's office.
The man, who is wanted by Belgian authorities, is "suspected of being a member of a terrorist organisation," Nuyts told AFP. His identity has not been revealed.
Eight people were arrested in Belgium on March 4th and charged with participating in the activities of a terrorist group. Six were released conditionally on March 25 while two were kept in detention.
Around 300 Belgian police officers conducted 28 searches to dismantle a network that was recruiting young volunteers to join the PKK, listed as a terrorist group by the European Union and the United States.
Belgian authorities issued a European arrest warrant for the man who was arrested in the Swedish capital on Friday after he was not found in the March raids, Nuyt said.
Belgium has made an extradition request, which is being review by Swedish authorities.