Related Rule
Ecuador
Practice Relating to Rule 28. Medical Units
Ecuador’s Naval Manual (1989) states:
Medical establishments and units (both mobile and fixed), … and medical equipment and stores may not be deliberately bombarded. Belligerents are required to ensure that such medical facilities are, as far as possible, situated in such manner that attacks against military targets in the vicinity do not imperil their safety. 
Ecuador, Aspectos Importantes del Derecho Internacional Marítimo que Deben Tener Presente los Comandantes de los Buques, Academia de Guerra Naval, 1989, § 8.5.1.4.
The manual further states:
If medical facilities are used for military purposes inconsistent with their humanitarian mission, and if appropriate warnings that continuation of such use will result in loss of protected status are unheeded, the facilities become subject to attack. 
Ecuador, Aspectos Importantes del Derecho Internacional Marítimo que Deben Tener Presente los Comandantes de los Buques, Academia de Guerra Naval, 1989, § 8.5.1.4.
The manual qualifies “deliberate attack upon medical establishments” as a war crime. 
Ecuador, Aspectos Importantes del Derecho Internacional Marítimo que Deben Tener Presente los Comandantes de los Buques, Academia de Guerra Naval, 1989, § 6.2.5.