"However, a Member State may, so far as is strictly necessary, refuse to notify the person concerned of ground, the disclosure of which might compromise State security." See: Press release, 4 June (pdf) And: Judgment
“However, a Member State may, so far as is strictly necessary, refuse to notify the person concerned of ground, the disclosure of which might compromise State security.”
See: Press release, 4 June (pdf)
And: Judgment in Case C-300/11, ZZ v Secretary of State for the Home Department (link)