Exceptions to the informing requirements
The controller is exempt from the obligation to inform the data subject pursuant to Articles 13 and 14 GDPR in certain cases, e.g. if such information would jeopardize the proper performance of the controller’s tasks, public security or the defense of legal claims.
Exemptions for public bodies
… if notifying data subjects about the processing would jeopardize the proper performance of tasks relating to national security, defense, public security, criminal offences and penalties, threats to public security or other important objectives of general public interest of the EU or Greece. Furthermore, the information requirements do not apply if they would jeopardize a confidential transfer of data to public bodies.