An Act to provide for the Trial and Punishment of War Criminals#
Part III—War crimes
9 War crime to be indictable offence
(1) A person who:
(a) on or after 1 September 1939 and on or before 8 May 1945; and
(b) whether as an individual or as a member of an organisation;
committed a war crime is guilty of an indictable offence against this Act.
Individual criminal responsibility
Jurisdiction ratione temporis
EDIT.