Related Rule
New Zealand
Practice Relating to Rule 161. International Cooperation in Criminal Proceedings
New Zealand’s Military Manual (1992) provides: “[The 1977 Additional Protocol I] Art. 88 requires the parties to assist one another in connection with grave breaches, including cooperation in matters of extradition.” 
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.
New Zealand’s Military Manual (1992) states: “[The 1977 Additional Protocol I] Art. 88 requires the parties to assist one another in connection with grave breaches, including cooperation in matters of extradition.” 
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.
New Zealand’s Military Manual (1992) states with respect to the prosecution of alleged war criminals:
If the Party concerned does not institute proceedings against offenders, it may, subject to the provisions of its own law, hand such persons over for trial by any party to the Conventions which has made out a prima facie case. This reference to the local law makes the procedure subject to local extradition legislation and some countries are likely to argue that war criminals acting on governmental instruction are political offenders immune from extradition. This argument was expressly rejected by the Ghana Court of Appeal in Ex p. Schumann (1949) … when put forward to contest an extradition application in respect of a doctor involved in the extermination programme at the Auschwitz concentration camp. [The 1977 Additional Protocol I] Art. 88 requires the parties to assist one another in connection with grave breaches, including cooperation in matters of extradition. 
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.
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.