Anti-triad officers believe they have dealt a heavy blow against triads in Yuen Long following the arrest of 166 people during a five-day operation. Besides uncovering a brothel in an abandoned poultry and pig farm, officers also busted gambling dens and extortion rackets involving hawkers and minibus drivers. Other triad-related activities include the sale of fireworks and marked oil. According to Lo Mung-hung, acting chief superintendent of the Organised Crime and Triad Bureau, the operation was launched following a 27 per cent surge in triad-related cases in Yuen Long last year. He said 90 per cent of the 69 men arrested during the operation were members of the 14K or Wo Shing Wo - the two most active triad societies in the area. Mr Lo said undercover officers had infiltrated the two societies to gather intelligence and evidence. They moved in last Wednesday, when officers raided 21 locations in Yuen Long and arrested 29 men and 90 women. Among their targets was the converted brothel, discovered in a remote village. It had been in operation for about a year and served up to 50 customers, mostly workers from nearby garages and farms, a day. The farm, surrounded by a fence, was equipped with closed-circuit surveillance cameras. Mr Lo said another seven men were arrested on Friday for allegedly extorting money from hawkers in Yuen Long and Tin Shui Wai. Four of them, aged between 16 and 22, have been charged with blackmail and being members of a triad society. They will appear in Tuen Mun Court today. The remaining three men were released on $10,000 police bail and ordered to report back on January 23. Officers also arrested 11 men for extortion of minibus drivers operating in Yuen Long. In a joint operation with Customs, officers raided seven stations selling illegal marked oil and arrested seven people. On Saturday, officers swooped on three triad-controlled gambling establishments and arrested eight people. About $100,000 in cash and betting slips was seized. Officers also seized $500,000 worth of fireworks and arrested two people. Two flats believed to be used by triads to store weapons were raided, leading to one arrest. Twelve knives and 12 sharpened water pipes were seized. Eleven other people wanted for various offences, including wounding, were arrested. Mr Lo said similar operations would be carried out in other districts to curb triad activities.