Hong Kong police used pepper spray Friday night to disperse more than 100 protesters singing and chanting pro-democracy slogans in a shopping mall.
The protest was one of several small ones that went ahead on the May 1 Labour Day holiday despite rules that forbid public gatherings of more than four people.
They follow the arrest of 15 pro-democracy activists and former lawmakers last Saturday.
The demonstrations are a continuation of a movement that began last June to protest an extradition bill that would have allowed detainees in Hong Kong to be transferred to mainland China.
Although the bill was later withdrawn, the demonstrations continued for months before a lull starting in January as the coronavirus pandemic broke out.