Police and activists are bracing for further violence later on Saturday as protesters plan to converge on a rural Hong Kong town where suspected triad gangsters attacked protesters and commuters at a train station last weekend.
Police, widely criticised for failing to better protect the public from the triad raid in Yuen Long, have refused to allow the latest march on safety grounds.
Activists are insisting they will push ahead, with some planning to skirt the police ban by openly organising shopping and dining expeditions to the town, government-funded broadcaster RTHK reported.
Residents described a mounting police presence on Saturday morning, with force chiefs insisting they will still seek to keep order despite the ban. Extra fortifications have been placed around the local police station.
Activists told Reuters they fear the protest could turn violent, given feelings of palpable anger among protesters over last Sunday's events and a determination among some to challenge villagers they believe are close to long-standing triad groups in the area.
"The situation is escalating, and tomorrow could be the start of a more violent period," one told Reuters.
Local district councillors and rural hamlet chiefs earlier urged police to object to the march, citing grave concerns over public safety and fears symbolic village sites could be attacked.
Last Sunday, 100 white shirted men stormed the Yuen Long station in an attack that came hours after protesters marched through central Hong Kong and defaced China's Liaison Office - the leading symbol of Beijing's authority over the former British colony.
They attacked black-clad protesters returning from Hong Kong island, passers-by, journalists and lawmakers with pipes and clubs, leaving 45 people injured.
Reuters reported on Friday that a Liaison Office official had days earlier urged local village chiefs to drive away any activists from the town.
The Yuen Long attack and the encirclement of the Liaison Office marked new fronts in a protest movement that has intensified over the last two months and sparked the most direct challenge to the authority of China's President Xi Jinping.
The movement further mushroomed on Friday as thousands of activists thronged the arrivals halls of Hong Kong international airport.
Initially demanding the scrapping of a bill that would have allowed people to be sent to mainland courts for trial, marchers are also seeking independent inquiries into police use of force, the resignation of Hong Kong leader Carrie Lam and full democratic reform - anathema to Beijing's Communist Party leadership.
The protracted crisis is exposing fissures across Lam's administration, with police chiefs and rank-and-file officers enraged at an apology over last weekend's attacks by her Chief Secretary on Friday, apparently without consultation.
Matthew Cheung said the government would not shirk its responsibility "and the police's handling fell short of residents' expectations".
Britain handed Hong Kong over to Chinese rule in 1997 amid guarantees that its core freedoms and autonomy, including the right to protest and an independent judiciary, would be protected under a "one country, two systems" formula. Many fear those rights are under threat as Beijing's reach extends into the city.