Protesters gathered in Mong Kok, Kowloon district of Hong Kong, late on Sunday marking the fourth anniversary of a dispute that began over pop-up food stands.
Government health officials tried to shut down informal food sellers in the densely-populated area in 2016.
Street hawkers with pop-up food stalls are a common part of Lunar New Year celebrations.
In 2016, crowds clashed for hours with the police protesting against the government enforcement attempts. Police fired warning shots using live ammunition.
