Petrol bombs were hurled at a Hong Kong police station and dozens of people were arrested Sunday following a march against so-called parallel trading near the Chinese border.
The Democratic Party said about 10,000 people marched peacefully in Sheung Shui district, but violence erupted after police ordered protesters to disperse.
Several petrol bombs were thrown at the Sheung Shui police station, about 1.5 kilometres (a mile) from where the rally took place.
The Sunday protest comes during a period of heightened anti-mainland sentiment in Hong Kong, where a pro-democracy movement demanding greater freedoms from Beijing has raged for nearly seven months.