Related Rule
New Zealand
Practice Relating to Rule 161. International Cooperation in Criminal Proceedings
Section E. Cooperation with international criminal tribunals
New Zealand’s Military Manual (1992), regarding the prosecution of alleged war criminals, states:
By Art. 89 [of the 1977 Additional Protocol I] they [States parties] are obliged to act jointly or individually in cooperation with the United Nations in regard to serious “violations” of the [1949 Geneva] Conventions or [the 1977 Additional Protocol I]. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, § 1711.4, footnote 76.
In 1995, New Zealand adopted the International War Crimes Act, which enables it to cooperate with the International Criminal Tribunal for the former Yugoslavia, the International Criminal Tribunal for Rwanda, and any other Tribunal that the Governor-General of New Zealand declares to be a Tribunal for the purposes of the Act. 
New Zealand, International War Crimes Act, 1995.
New Zealand’s International Crimes and ICC Act (2000) states:
The purpose of this Act is
(b) to enable New Zealand to co-operate with the International Criminal Court established by the Rome Statute in the performance of its functions. 
New Zealand, International Crimes and ICC Act, 2000, Article 3b.