Portugal e Reino Unido assinaram em 14 de Junho de 1913, o acordo que regulamentava o monopólio do ópio nas colónias de Hong Kong e Macau.  Em 1 de Março de 1922, o Governo de S. Magestade Britânica denunciou esse acordo.

Extraído de «The Edinburgh Gazette», 7 de Março de 1922. Issue 13793 Page 416
Extraído de «NEWMAN, R. K. – India and the Anglo-Chinese Opium Agreements 1907-14

International Opium Convention, signed at The Hague on January 23, 1912 during the First International Opium Conference, was the first international drug control treaty. It was registered in League of Nations Treaty Series on January 23, 1922.[1] The United States convened a 13-nation conference of the International Opium Commissionin 1909 in Shanghai, China in response to increasing criticism of the opium trade. The treaty was signed by Germany, the United StatesChinaFrance, the United KingdomItalyJapan, the NetherlandsPersiaPortugalRussia, and Siam. “ (https://en.wikipedia.org/wiki/International_Opium_Convention)

“During most of the period from 1912 to 1936, Guangdong Province was independent from the central government. The local authorities there were facing a dilemma regarding opium, as others were elsewhere in China. On the one hand, opium was considered the symbol of China’s weakness, and its suppression was a top priority; on the other hand, opium taxes represented an indispensable source of fiscal income. Some Guangdong power holders were truly committed to a suppression agenda, especially from 1913 to 1924. During this period, with the exception of a brief interlude from 1915 to 1916, opium laws were prohibition laws. Even if these laws were not always enforced with full vigor, the drug remained illegal in Guangdong. (Unacceptable but Indispensable: Opium Law and Regulations in Guangdong, 1912–1936. Xavier Paulès, École des Hautes Études en Sciences Sociales, Paris.)