Sweden's national prosecutor said on Thursday a 50-year-old man had been charged with illegally spreading classified information about a large number of defence installations.
"I consider it a gross violation as the information concerned issues of significant importance to the nation's defence," senior prosecutor Lars Hedvall said in a statement.
Any disclosure of the information to a foreign power could cause major damage to the Nordic nation's defence and reduce its ability to defend itself in a war, he added.
The Swedish security service had investigated the matter, the prosecutor said.
(Reporting by Essi Lehto, editing by Terje Solsvik)