Related Rule
Practice Relating to Rule 146. Reprisals against Protected Persons
Section D. Civilians in the power of the adversary
Sweden’s IHL Manual (1991), referring to Article 33 of the 1949 Geneva Convention IV, states:
Protected persons may not be punished for actions they have not themselves performed. Collective punishment of a whole group is also prohibited. Also, the occupying power may not punish protected persons … in reprisal for some action directed against the occupying power. If disturbances occur, the occupant may not attempt to restore order by taking innocent persons hostage. 
Sweden, International Humanitarian Law in Armed Conflict, with reference to the Swedish Total Defence System, Swedish Ministry of Defence, January 1991, Section 6.1.3, p. 122.