Geneva Convention relative to the Treatment of Prisoners of War, UNHCHR
Article 13: (...) Likewise, prisoners of war must at all times be protected, particularly against acts of violence or intimidation and against insults and public curiosity.
Article 17: Every prisoner of war, when questioned on the subject, is bound to give only his surname, first names and rank, date of birth, and army, regimental, personal or serial number, or failing this, equivalent information. If he wilfully infringes this rule, he may render himself liable to a restriction of the privileges accorded to his rank or status. (...)
No physical or mental torture, nor any other form of coercion, may be inflicted on prisoners of war to secure from them information of any kind whatever. Prisoners of war who refuse to answer may not be threatened, insulted, or exposed to any unpleasant or disadvantageous treatment of any kind.