Related Rule
New Zealand
Practice Relating to Rule 46. Orders or Threats That No Quarter Will Be Given
New Zealand’s Military Manual (1992) states: “It is prohibited to order that no prisoners will be taken, to threaten an adverse party that such an order will be given, or to conduct hostilities on the basis that no prisoners will be taken.” 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, § 503(1) (land warfare); see also § 612(1) (air warfare).
The manual also provides that “declaring that no quarter will be given” is a war crime. 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, § 1704(2)(d).
The manual further states: “Article 4(1) of [the 1977 Additional Protocol II] extends to non-international armed conflicts the principle of customary international law that it is prohibited to order that there shall be no survivors.” 
New Zealand, Interim Law of Armed Conflict Manual, DM 112, New Zealand Defence Force, Headquarters, Directorate of Legal Services, Wellington, November 1992, § 1811.
Under New Zealand’s International Crimes and ICC Act (2000), war crimes include the crimes defined in Article 8(2)(b)(xii) and (e)(x) of the 1998 ICC Statute. 
New Zealand, International Crimes and ICC Act, 2000, Section 11(2).