Related Rule
Germany
Practice Relating to Rule 79. Weapons Primarily Injuring by Non-Detectable Fragments
Germany’s Military Manual (1992) prohibits the use of “any weapon the primary effect of which is to injure by fragments which in the human body escape detection by X-rays”. 
Germany, Humanitarian Law in Armed Conflicts – Manual, DSK VV207320067, edited by The Federal Ministry of Defence of the Federal Republic of Germany, VR II 3, August 1992, English translation of ZDv 15/2, Humanitäres Völkerrecht in bewaffneten Konflikten – Handbuch, August 1992, § 408.
Germany’s IHL Manual (1996) states:
International humanitarian law prohibits the use of a number of means of warfare, which are of a nature to violate the principle of humanity and to cause unnecessary suffering, e.g. … weapons whose primary effect is to injury by fragments which in the human body escape detection by X-rays, e.g. plastic or glass ammunition. 
Germany, ZDv 15/1, Humanitäres Völkerrecht in bewaffneten Konflikten – Grundsätze, DSK VV230120023, Bundesministerium der Verteidigung, June 1996, § 305.