The arrest took place Sunday, a Sapo spokesman told dpa, but declined to offer details of which country the suspect had spied for or his nationality.
He also declined to say how long the illegal information gathering on members of the Tibetan community in Sweden had gone on for.
Combating espionage on refugees and exiled dissidents is one of Sapo‘s tasks to ensure that people granted asylum can exercise their democratic rights and freedoms.
China seized Tibet in 1950. Nine years later the Dalai Lama, Tibet‘s religious leader, and 100,000 of his supporters fled into exile.
China has featured in past Sapo probes involving cases of spying on refugees in Sweden. Iran and Eritrea are other countries mentioned in recent years.