ICAO Annex 13 may help; particularly paragraph 5.12.1
Annex 13 extract
Non-disclosure of records
5.12 The State conducting the investigation of an accident
or incident shall not make the following records available for
purposes other than accident or incident investigation, unless
the appropriate authority for the administration of justice in
that State determines that their disclosure outweighs the
adverse domestic and international impact such action may
have on that or any future investigations:
a) all statements taken from persons by the investigation
authorities in the course of their investigation;
b) all communications between persons having been
involved in the operation of the aircraft;
c) medical or private information regarding persons
involved in the accident or incident;
d) cockpit voice recordings and transcripts from such
recordings; and
e) opinions expressed in the analysis of information,
including flight recorder information.
5.12.1 These records shall be included in the final report
or its appendices only when pertinent to the analysis of the
accident or incident. Parts of the records not relevant to the
analysis shall not be disclosed.