The growing use of force by anti-government protesters in Hong Kong took a new twist over the weekend, with vigilantism being advocated as a way to tackle clashes with rival groups. As the city marked the 15th straight weekend of demonstrations, protesters used a new phrase – si liu – which is Cantonese for “resolving things privately”.

The line advocates physical retaliation against aggressive groups rather than retreating or asking police – whom many widely view as their enemy – to mediate and enforce the law.

Such calls intensified online following attacks on Saturday at Fortress Hill, when a group of men in blue T-shirts with the slogan “I love police” were seen openly beating civilians with wooden sticks and Chinese national flags near a “Lennon Wall”.

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Previously, clashes in Tsuen Wan, North Point, and Yuen Long had seen groups of older men attacking black-clad protesters.

Other clashes at Lennon Walls include one incident on July 11 in Kowloon Bay where a young man did not resist when punched multiple times. In another clash in Tseung Kwan O in the early hours of August 20, three people were badly injured in a knife attack. In both cases, the attackers were arrested.

Over four days, from last Saturday to Tuesday morning, more than 140 discussion threads about fighting back were posted on LIHKG, an online forum used by protesters. But for a month before Saturday, there were only about 50 discussion threads on the same subject.

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The call for fist fights comes on top of an array of tactics used by anti-government protesters over the past three months, each appearing more violent than previous methods.

Teresa Kwok, 14, from South Island School, thinks violence will not help. “People are just going to fight against each other and it will never stop,” Teresa says. “I truly think that protesters should respect other people’s political views, not fight them, and convince them to believe who is wrong and who is right.”