Related Rule
Spain
Practice Relating to Rule 65. Perfidy
Section J. Simulation of protected status by using flags or military emblems, insignia or uniforms of neutral or other States not party to the conflict
Spain’s LOAC Manual (1996) provides that “simulating possession of a protected status by using signs, emblems or uniforms … of neutral States or other States which are not Parties to the conflict” is an example of perfidy. 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Publicación OR7-004, 2 Tomos, aprobado por el Estado Mayor del Ejército, Division de Operaciones, 18 March 1996, Vol. I, § 3.3.b.(1); see also § 5.3.c.
Spain’s LOAC Manual (2007) prohibits the act of perfidy and states that “the feigning of protected status by the use of signs, emblems or uniforms of … neutral or other States not Parties to the conflict” is an example of such an act. 
Spain, Orientaciones. El Derecho de los Conflictos Armados, Tomo 1, Publicación OR7–004, (Edición Segunda), Mando de Adiestramiento y Doctrina, Dirección de Doctrina, Orgánica y Materiales, 2 November 2007, § 2.3.b.(3); see also §§ 3.3.b.(1).(d) and 5.3.c.
Spain’s Penal Code (1995) punishes “anyone who, during an armed conflict … uses … in a perfidious manner the flag, uniform, insignia or distinctive emblem of neutral States … or of other States which are not parties to the conflict”. 
Spain, Penal Code, 1995, Article 612(5).