12.08.1949|Legislation & Conventions|International Convention
Geneva Convention (IV) relative to the Protection of Civilian Persons in Time of War (1949)
Article 106
The Article states that an internee has the right to send, soon after his arrival, a card to his family and to the Central Agency for protected persons, informing his relatives of his detention, address, and state of health. The detaining authority shall send the card as rapidly as possible and without delay. From ICRC website.