Related Rule
United Kingdom of Great Britain and Northern Ireland
Practice Relating to Rule 53. Starvation as a Method of Warfare
Section A. General
The UK LOAC Pamphlet (1981) provides: “It is forbidden … to starve civilians as a method of warfare.” 
United Kingdom, The Law of Armed Conflict, D/DAT/13/35/66, Army Code 71130 (Revised 1981), Ministry of Defence, prepared under the Direction of The Chief of the General Staff, 1981, Section 4, p. 14, § 5(f).
The UK LOAC Manual (2004) states: “Starvation of civilians as a method of warfare is prohibited.” 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, § 5.27.
With regard to internal armed conflict, the manual provides:
15.19. Starvation of civilians as a method of warfare is prohibited.
15.19.1. The right to life is a non-derogable human right. Violence to the life and person of civilians is prohibited, whatever method is adopted to achieve it. It follows that the destruction of crops, foodstuffs and water sources, to such an extent that starvation is likely to follow, is also prohibited. The same applies to sieges, blockades, embargoes, or the blocking of relief supplies with the intention of causing starvation. 
United Kingdom, The Manual of the Law of Armed Conflict, Ministry of Defence, 1 July 2004, §§ 15.19–15.19.1.
Under the UK ICC Act (2001), it is a punishable offence to commit a war crime as defined in Article 8(2)(b)(xxv) of the 1998 ICC Statute. 
United Kingdom, ICC Act, 2001, Sections 50(1) and 51(1) (England and Wales) and Section 58(1) (Northern Ireland).
In 1990, in the UN Sanctions Committee on Iraq, the United Kingdom considered that “no one favoured allowing the inhabitants of Kuwait and Iraq to starve”. 
United Kingdom, Statement before the UN Security Council Committee Established by Resolution 661 (1990) concerning the Situation between Iraq and Kuwait, UN Doc. S/AC.25/SR.5, 12 September 1990, p. 5.
According to the Report on UK Practice, the United Kingdom supports the protection of civilians against starvation and the condemnation of starvation of civilians as a tactic in armed conflict. 
Report on UK Practice, 1997, Chapter 4.1.