The two men were arrested in Finnish Lapland and remanded in custody last week. According to the police, the investigation has not yielded enough evidence to justify continued detention, according to the radio.
The investigation continues and there are still suspicions against the men, who are in their 40s and registered at an address in Västernorrland.
The espionage crime is suspected to have been committed at the turn of August and September, the police say.
The men are suspected of having taken photographs in areas near objects critical to Finland's security of supply, according to Swedish Yle.
