Related Rule
United Kingdom of Great Britain and Northern Ireland
Practice Relating to Rule 100. Fair Trial Guarantees
Section G. Examination of witnesses
The UK Military Manual (1958) provides, regarding disciplinary punishment of a prisoner of war: “He must be allowed to call witnesses.” 
United Kingdom, The Law of War on Land being Part III of the Manual of Military Law, The War Office, HMSO, 1958, § 208.
The manual further provides that “in any judicial proceedings against him, the prisoner of war is entitled to … call witnesses” and that “Defending Counsel … must also be allowed to interview any witness for the defence, including prisoners of war”. 
United Kingdom, The Law of War on Land being Part III of the Manual of Military Law, The War Office, HMSO, 1958, § 227.
With respect to cases of occupation, the manual states that the “accused have the right to present evidence necessary to their defence and may, in particular, call witnesses”. 
United Kingdom, The Law of War on Land being Part III of the Manual of Military Law, The War Office, HMSO, 1958, § 571.
The UK LOAC Manual (2004) states in its chapter on the protection of civilians in the hands of a party to the conflict:
In the case of penal offences relating to the armed conflict, the basic principles of natural justice must be observed … These principles include the following: … anyone charged with an offence shall have the right to examine, or have examined, the witnesses against him and to obtain the attendance and examination of witnesses on his behalf under the same conditions as witnesses against him. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 9.6.
The manual also provides that before awarding any disciplinary punishment to a civilian internee, “the accused must be … given an opportunity to … to defend himself. In particular, he must be allowed to call witnesses …”. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 9.9.
In its discussion on judicial proceedings against prisoners of war, the manual states: “In good time before the trial to enable him to exercise them, the accused must be informed of his rights to … call witnesses.” 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 8.133.
In its discussion on disciplinary measures against prisoners of war, the manual states: “Before any disciplinary award is announced, the accused … must be allowed to call witnesses.” 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 8.125.
Furthermore, in its discussion on the administration of criminal law in occupied territory, the manual provides that the accused “are entitled to … personal presence at the trial including the facility to present necessary evidence for the defence, calling witnesses as required”. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 11.58 11 .
Lastly, in its chapter on internal armed conflict, the manual states: “Indispensable judicial guarantees include as a minimum … the attendance of both prosecution and defence witnesses.” 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 15.30.5.