File photo.

A 35-year-old Bulgarian man was arrested Saturday in Thessaloniki, northern Greece, on suspicion of espionage after police said he flew a drone without authorization and was found in possession of sensitive imagery.

According to the Hellenic Police, the case began after a resident in eastern Thessaloniki reported a drone operating in the area. Officers from the DIAS motorcycle unit located the man and determined he did not hold the required pilot’s license.

Police said a drone was discovered in his vehicle during the search. A review of stored data allegedly revealed a thermal image of facilities at the former Farmaki military camp in Kalamaria.

A case file was opened against the suspect, who is expected to be referred to a public prosecutor. Authorities have not released further details about the investigation.