The Swedish domestic security agency says a person has been arrested on suspicion of spying on refugees who fled to Sweden.

The agency, known as SAPO, said Thursday the unidentified person was arrested a day earlier, adding it had been working on the case "for a long time."

SAPO said the espionage is a way "of trying to prevent refugees from expressing criticism of the regime in the country they have fled," adding the agency "conducts active work to prevent and counteract the spying on refugees that occurs in Sweden."

In June, a 49-year old Tibetan man was found guilty of spying for China by gathering information on Tibetans who had fled to Sweden. A court sentenced him to 22 months in jail.