Соответствующая норма
Practice Relating to Rule 107. Spies
Section B. Status of spies
Nigeria’s Military Manual (1994) states: “Spies … are however not to be considered as prisoner[s] of war.” 
Nigeria, International Humanitarian Law (IHL), Directorate of Legal Services, Nigerian Army, 1994, p. 8, § 9(c)(2).
Nigeria’s Manual on the Laws of War states:
For the purpose of waging war it is necessary to obtain information about the enemy. To get such information, it is lawful to employ spies and use soldiers and civilians of the enemy for committing acts of treason. But although this practice by the states is considered legitimate, lawful punishment under the municipal law may be imposed upon individuals engaged in espionage or treason when they are caught by the enemy … Soldiers wearing their uniform when penetrating the enemy zone of operations are not spies and if captured, should be treated as prisoners of war. When a spy is apprehended, he should not be punished without a fair regular trial. A spy who succeeds to rejoin his armed forces and is subsequently captured by the enemy is not liable to be punished for his previous acts of espionage. Such immunity is not accorded to a civilian spy captured by the enemy after reaching his own territory. 
Nigeria, The Laws of War, by Lt. Col. L. Ode PSC, Nigerian Army, Lagos, undated, § 31.