During the weekend protests, website Hong Kong Free Press showed footage of one arrest that appeared to include officers dressing as protesters who injured a demonstrator pressed to the ground.
The young man, who said his name was Chow Ka-lok and asked for a lawyer, was left with bleeding head wounds and a broken tooth.
Police have also reported injuries among their ranks, including eye irritation from laser pointers and burns from a petrol bomb.
Protesters hurled bricks at officers and ignored warnings to leave before tear gas was deployed in the Sham Shui Po area, police said, calling a march there an "unauthorized assembly."
Tear gas was also deployed in central Hong Kong on both sides of Victoria Harbour, in the Tsim Sha Tsui area on the Kowloon side and in Wan Chai on Hong Kong Island. At one point, protesters blocked the entrance to a plaza to prevent police from entering.
A train station in Kwai Fong filled with smoke after about a dozen police officers fired tear gas inside. It was not clear how many protesters were inside the station at the time, but it has been rare for officers to fire tear gas indoors.
Earlier, a large group of mostly young protesters marched down the middle of Hennessey Road, a main shopping drag in the Causeway Bay area, as a rally was held in nearby Victoria Park. Many wore face masks to shield their identities, and a few had helmets. Others just carried backpacks over the black T-shirts that have become their uniform.
The protest movement's demands include the resignation of the Chinese territory's leader, Carrie Lam, democratic elections for her successor, the release of those arrested in earlier protests and an investigation into police use of force.
A former British colony, Hong Kong was returned to China in 1997 under the principle of "one country, two systems," which promises the city certain democratic rights not afforded to people on the mainland. But in recent years, some have accused the Communist Party-ruled central government of steadily chipping away at their freedoms.
Banners at the rally in Victoria Park read "Give Hong Kong back to us" and "Withdraw the evil law," the latter a reference to an extradition bill that was the original spark for the protests. A large crowd sat under umbrellas, which are both a protest symbol in Hong Kong and protection from the summer heat.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)
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