Thousands take to the streets to march against Chinese traders in what is fast becoming a summer of unrest in the semi-autonomous territory.
Demonstrations took place on Saturday in Sheung Shui, a district that lies across the border from the mainland city of Shenzhen.
Major protests have taken place in the past month against a proposal to change extradition laws.
Demonstrators walked behind a banner reading "strictly enforce the law, stop cross-border traders" on Saturday.
The protesters passed by pharmacies and cosmetic shops that are popular with Chinese tourists and traders who bring goods back to sell on the mainland.
Clashes broke out between police and some of the protesters towards the end of the otherwise peaceful march.
Officers used pepper spray and batons to disperse the crowd, public broadcaster RTHK reported.
Reporting from IRN.