The arrest took place on Wednesday, the Dagens Nyheter newspaper said. It cited public prosecutor Hans-Jorgen Hanstrom who said the suspect was active between April 10 and September 30, 2018.
Earlier, Swedish police detained a man suspected of spying for Russia.
According to the Swedish Security Police (SAPO), the suspect was allegedly recruited by a Russian intelligence officer working under diplomatic cover.
The suspect, who was working in Sweden in the hi-tech sector, was arrested late on Tuesday in central Stockholm, according to police.