The gathering in Victoria Park unfurled umbrellas to form the shape 2012, the year by which they want the right to elect the Chinese territory's chief executive and legislature, the BBC reported.
Presently, the chief executive is named by an 800-member panel, much of which favors Beijing over Hong Kong, and only half of the legislature is elected directly.
Chinese officials have spent the last three months debating political reform for Hong Kong, a former British colony put under Chinese control in 1997.
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