Hong Kong protesters plan to rally on Thursday evening to show solidarity with people demonstrating in Spain's wealthiest region of Catalonia over jail sentences handed out to nine separatist leaders.
The protests in Catalonia share some noticeable comparisons with the demonstrations in Hong Kong, where millions have taken to the streets for five months to vent their anger over what they see as Beijing's tightening grip on the city.
Most protesters in Hong Kong want greater democracy, among other demands, although a small minority are calling for independence, a red line for Communist Party leaders in Beijing.
Independence is also a highly divisive issue in Catalonia, which, like Hong Kong, has more than 7 million inhabitants, its own language, parliament and flag.
Some demonstrators waved the Catalonian flag at a protest in Hong Kong on Sunday, while activists in Spain's northeastern region have adopted some of the tactics used by people in the Chinese-ruled city.
Students in Catalonia have boycotted classes, while protesters there have focused on strategic targets to cause maximum disruption, including the international airport serving Barcelona - similar to strategies used by Hong Kong activists.
Catalonian demonstrators are angry at what they see as attempts to thwart their desire for greater autonomy from the rest of Spain, fears that resonate with many protesters in the former British colony of Hong Kong.
Some Hong Kong protesters are going online ahead of the demonstration to urge people not to attend, saying it is too provocative and risks denting international support for their cause.
Hong Kong authorities formally banned a group promoting independence from China in September last year, the first outlawing of a political organisation since the handover.
Under the terms of the 1997 handover from Britain, Hong Kong was allowed to retain extensive freedoms not enjoyed in mainland China under a "one country, two systems" formula, including an independent judiciary and right to protest.
However, many Hong Kong residents are angry at what they see as a relentless march towards mainland control.
Hong Kong's legislature formally withdrew on Wednesday planned legislation that would have allowed extraditions to mainland China, a bill that triggered the unrest, but the move was unlikely to end the protests because it met just one of the pro-democracy demonstrators' five demands.