The suspect, a Polish citizen employed at one of the factories belonging to the state-controlled Polska Grupa Zbrojeniowa (PGZ), was detained two days earlier following an investigation by Poland's military counterintelligence service, Kosiniak-Kamysz said in a post on X.
Kosiniak-Kamysz said prosecutors in the western city of Poznań had brought espionage charges against the man and that the District Court in Poznań ordered him held in pre-trial detention for three months.
The investigation was conducted by Poland's Military Counterintelligence Service (SKW) with support from the Internal Security Agency (ABW), he added.
Kosiniak-Kamysz said the suspect was charged with "providing information to a foreign intelligence service that could harm the interests of the Polish state."
Under Polish law, the offence carries a minimum prison sentence of eight years and can be punishable by life imprisonment.
"Another espionage suspect in custody; good work by the SKW, ABW and prosecutors," Tomasz Siemoniak, the government minister responsible for coordinating Poland's intelligence services, wrote on X.
PGZ is Poland's largest state-owned defence group and includes dozens of companies producing weapons and military equipment, among them Huta Stalowa Wola, Fabryka Broni Łucznik-Radom, Wojskowe Zakłady Motoryzacyjne and H. Cegielski Poznań.
The group is overseen by the Polish Ministry of State Assets and is one of the main suppliers of equipment to the country's armed forces.
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Source: IAR, PAP