One of the suspects had allegedly passed on information about Sweden and another unnamed country.
Swedish authorities say they have arrested two more people on suspicion of spying after early morning raids in Stockholm.
The suspects were detained in absentia after house searches by Sweden’s security agency (SÄPO), police, and the Swedish Armed Forces.
Swedish media have reported that the suspects are a couple in their 60s and that two Black Hawk helicopters were used in the police operation.
"One of the detainees is suspected of aggravated unlawful intelligence activities against Sweden and against a foreign power," SÄPO said in a statement.
"The other person is suspected of aiding and abetting," it added."A preliminary investigation has been ongoing for some time."
A third individual has been taken in for questioning in connection with the case. No further details were given.
The raids come after Swedish authorities charged two Iranian-born brothers with alleged spying for Russia's military intelligence service (GRU) for around 10 years. One of the suspects had worked for Sweden’s domestic intelligence agency. Both have denied any wrongdoing.
Swedish prosecutors said there was no link between the two cases.