16 February 2015 Last updated at 05:01
- In pictures: Hong Kong 'parallel trade' protests
- Angry protests have taken place in a shopping centre in Hong Kong against mainlanders who visit the territory to shop.
Hong Kong residents have long complained about mainlanders buying up goods at lower tax rates and then selling them on at home at a profit, so-called parallel trading.
They say this leaves Hong Kongers with a shortage of basic supplies and pushes up the cost of goods, while also accusing the mainlanders of bad behaviour.
Tens of millions of mainlanders visit Hong Kong every year, many for just a day. The protesters compare them to locusts, saying they are taking advantage of Hong Kong's lack of a goods and services tax.
The protesters gathered on Sunday at the New Town Plaza shopping centre in Sha Tin, surrounding mainland shoppers and heckling them. It was the second such protest in a week.
This time of year is a particularly busy shopping period as people stock up on food and gifts ahead of Lunar New Year celebrations. This man was being detained by protesters who accused him of beating someone up.
least one protester waved a Hong Kong colonial-era flag, a symbol often used by the pro-independence movement in the former British colony.
Hong Kong's media said a number of people were arrested as protesters clashed with police, who deployed pepper spray to hold them back.
This mainland woman was watching the unrest from behind a shop shutter. One shopper visiting from Hangzhou told the South China Morning Post: "This is crazy, I don't know why they are so violent. I have only come to buy gifts for the Lunar New Year, I guess I won't spend so much here in the future."
The issue of parallel trading has been rumbling for several years and is seen as a factor in rising anti-mainland sentiment in Hong Kong.
The authorities do conduct occasional sweeps and arrest parallel traders under immigration offences, but the protesters want a bigger crackdown.