The historical enmity between Britain and China will be remembered as part of a pro-mainland group's handover celebrations.
Young people from Hong Kong and Guangdong will join hands in a mock opium-destroying ceremony in Humen, Dongguan, on June 15.
The organisers, Hong Kong United Youth Association, said Humen was chosen because it was where the ancient Qing dynasty's imperial commissioner Lin Zexu destroyed British opium in 1839. His act triggered the Opium War, resulting in the Treaty of Nanking in which Hong Kong was ceded.
An association spokesman said: 'Opium gave great humiliation to China, making us lose Hong Kong to the British. It is a part of history which young people should not forget.' The June ceremony would symbolise China 'washing out indignity' with Hong Kong's return to the motherland.