LAW on the Implementation of the Statute of the International Criminal Court and the Prosecution of Crimes against International Law of War and Humanitarian Law
III. NOTIFICATION T O THE PROSECUTOR AND ACTION T O BE TAKEN UPON THE PROSECUTOR'S NOTIFICATION
Article 18
(1) When the Prosecutor notifies the Republic of Croatia that there would be a reasonable basis to commence an investigation for a crime defined in Article 5 of the Statute and that the component Croatian authorities may exercise jurisdiction over the crime concerned, the Government of the Republic of Croatia shall notify thereon the Public Attorney General.
(2) If the notification referred to in the foregoing paragraph is confidential, its content shall be treated as an official secret by any state authorities or persons to which or to whom this content has been brought to notice.
Complementarity
Deferral of case by ICC to State
Confidentiality re request for cooperation and supporting documentation
EDIT.