Règle correspondante
Sweden
Practice Relating to Rule 13. Area Bombardment
Sweden’s IHL Manual (1991) states:
If the military objectives are located in a densely-populated area which has been evacuated only to a limited extent if at all, area bombardment may not be employed since this would be a breach of the basic rule prohibiting indiscriminate attack. Moreover, area bombardment would most probably lead to excessive injury and losses, and would thus be a breach of the proportionality rule. 
Sweden, International Humanitarian Law in Armed Conflict, with reference to the Swedish Total Defence System, Swedish Ministry of Defence, January 1991, Section 3.2.1.5, p. 47.