(Recasts as protesters spread through area)
By Donny Kwok and Simon Gardner
HONG KONG, Aug 3 (Reuters) - Stores in the heart of Hong Kong's Kowloon shopping area shut their doors on Saturday and black-clad activists blocked thoroughfares as the Chinese-controlled city was again rocked by anti-government protests.
Tens of thousands marched through the crowded Mong Kok district in the afternoon, with many then dispersing to different parts of the Kowloon peninsula, where they defaced police station signs and set up barriers across busy streets.
Police said a large group of protesters had marked the Tsim Sha Tsui police station, in one of Kowloon's shopping districts, with paint and damaged a vehicle inside the station. The police said in a statement that officers had warned them "to stop their illegal act at once and disperse peacefully".
Riot police could be seen outside the police stations in Tsim Sha Tsui and Mong Kok.
Protests against a proposed bill allowing people to be extradited to stand trial in mainland China have grown increasingly violent since June, with police accused of excessive force and failing to protect protesters from suspected gang attacks.
Protesters, their faces covered with masks or bandanas and wearing helmets and goggles, have adopted increasingly sophisticated tactics. On Saturday, many carried hiking sticks and some held homemade shields.
"We don't stay in the same place. We are using hit-and-run tactics," said a construction worker who was among protesters in the Mong Kok area of Kowloon and called himself "Water".
"If the police are too strong, we will leave. They are a rock, so we must be like water," he added, echoing a refrain of Hong Kong martial arts legend Bruce Lee that has been taken up by activists.
In the Nathan Road area, ordinarily packed with Saturday shoppers, shutters were down on most street-facing shops, including 7-11 convenience stores, jewellery chain Chow Tai Fook and watch brands Rolex and Tudor.
The main entrance of the landmark Peninsula Hotel was closed.
Gary, 25, a digital marketeer, said protesters were coordinating via Instagram, Facebook and Telegram, and that they had appealed against further violence.
"We haven't put up many barricades," he said. "We want this to be a peaceful protest. We have asked everyone to avoid violence in the hope the police won't crack down. It's weird, there are no police around."
Many of Saturday's demonstrators wore yellow or white hard hats, and the crowds chanted "age of revolution!" and "Hong Kongers, add oil!" - a popular exhortation in Cantonese.
Earlier, hundreds of marchers held posters with an illustration of protesters in hard hats tending to a young child, with the words "protect the future".
The crowd was mostly young, but also included families and many older people. Some young couples held hands.
As the marchers gathered at the starting point, one passed around pre-paid subway cards to young groups, while others gave out chicken wings and McDonald's food. When the march started, volunteers handed out hard hats, face masks and water bottles.
Organizers put the size of the crowd for the rally at 120,000. Police had yet to release their estimate.
Across the harbour, on Hong Kong island, thousands of police supporters, mostly wearing white, held a separate afternoon rally amid a carnival-like atmosphere in Victoria Park.
Many waved Hong Kong and Chinese flags and the crowd shouted slogans in support of the police. Pro-Beijing lawmaker Junius Ho was greeted with strong applause.
"We are the real Hong Kong people who are not the same as those black-shirted thugs. We don't need a so-called 'HK revolution', we only need to do our best, which is enough," he told the crowd.
Sylvia Lam, 61, who described herself as a housewife, said she had turned up at the pro-police rally to oppose violence.
"I feel extremely uncomfortable when every time I watch TV, the scenes are so radical," she said. "Young people should stop and think, don't become someone's political tools, be rational please."
The organiser estimated the size of the crowd at the pro-police event as 90,000, while the police said the crowd numbered 26,000 at its peak.
MORE PROTESTS PLANNED
Further anti-government protests were scheduled for Sunday, with activists calling for a mass strike on Monday.
Months of demonstrations are taking a growing toll on the city's economy, with local shoppers and tourists avoiding parts of one of the world's most famous shopping destinations.
On Friday evening, in central Hong Kong, thousands of civil servants had defied a warning from authorities to remain politically neutral and joined anti-government protests for the first time since they started two months ago.
In Washington on Friday, a bipartisan group of U.S. lawmakers called on the Trump administration to halt future sales of munitions and crowd-control equipment to Hong Kong's police force, which has been accused of using excessive force against protesters.
Under Chinese rule, Hong Kong has been allowed to retain extensive freedoms, such as an independent judiciary, but many residents see the extradition bill as the latest step in a relentless march towards mainland control.
The protests are the most serious political crisis in Hong Kong since it returned to China 22 years ago.
They also pose the greatest popular challenge to Chinese leader Xi Jinping since he took office in 2012 and come as Xi grapples with an escalating trade war with the United States and a slowing economy in a politically sensitive year. On Oct. 1, China will mark the 70th anniversary of the founding of the People's Republic. (Reporting by Anne Marie Roantree, Sumeet Chatterjee, Vimvam Tong, Donny Kwok, Twinnie Siu, Kevin Liu, Felix Tam, Marius Zaharia, Joyce Zhou, and Simon Gardner; Writing by Tony Munroe; Editing by Michael Perry and Alex Richardson)
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