The Fourth Geneva Convention

The Fourth Geneva Convention covers humanitarian protection for civilians in a war zone. It is part of customary international law, and as such is also binding on States which are not formally parties to it. Article 1 states that The High Contracting Parties undertake to respect and to ensure respect for the present Convention in all circumstances. Article 33 states No protected person may be punished for an offence he or she has not personally committed. Collective penalties and likewise all measures of intimidation or of terrorism are prohibited. Pillage is prohibited. Reprisals against protected persons and their property are prohibited.

Article 47 states

Protected persons who are in occupied territory shall not be deprived, in any case or in any manner whatsoever, of the benefits of the present Convention by any change introduced, as the result of the occupation of a territory, into the institutions or government of the said territory, nor by any agreement concluded between the authorities of the occupied territories and the Occupying Power, nor by any annexation by the latter of the whole or part of the occupied territory.

Article 49 states

Individual or mass forcible transfers, as well as deportations of protected persons from occupied territory to the territory of the Occupying Power or to that of any other country, occupied or not, are prohibited, regardless of their motive. Nevertheless, the Occupying Power may undertake total or partial evacuation of a given area if the security of the population or imperative military reasons so demand. Such evacuations may not involve the displacement of protected persons outside the bounds of the occupied territory except when for material reasons it is impossible to avoid such displacement. Persons thus evacuated shall be transferred back to their homes as soon as hostilities in the area in question have ceased.
The Occupying Power undertaking such transfers or evacuations shall ensure, to the greatest practicable extent, that proper accommodation is provided to receive the protected persons, that the removals are effected in satisfactory conditions of hygiene, health, safety and nutrition, and that members of the same family are not separated.
The Protecting Power shall be informed of any transfers and evacuations as soon as they have taken place.
The Occupying Power shall not detain protected persons in an area particularly exposed to the dangers of war unless the security of the population or imperative military reasons so demand.
The Occupying Power shall not deport or transfer parts of its own civilian population into the territory it occupies.