Chapter 16. Genocide, crimes against humanity and war crimes
Section 107. War crimes consisting in the use of prohibited means of warfare
Any person is liable to punishment for a war crime who in connection with an armed conflict
d) employs another means of warfare that is in violation of international law
Employing asphyxiating, poisonous or other gases, and all analogous liquids, materials or devices - IAC
Employing weapons, projectiles and materials and methods of warfare which cause superfluous injury or unnecessary suffering - IAC
EDIT.