TWO men were arrested after demanding a $120,000 protection fee from an undercover policeman posing as a construction company boss, the District Court heard yesterday. Car cleaner Choi Siu-ming, 22, and transport workers Lee Wing-fai, 22, Pui Kam-chuen, 25, and Chow Kin-hung, 22, were found guilty of various offences relating to the protection racket. Prosecuting counsel Mr Steve Chui said Choi and an unknown man, went to an Aberdeen construction site and told the site foreman they belonged to the Wo Hop To triad society. They demanded the decoration contracts for the building. On March 10, 1992, scorch-marks were discovered on a wall and piping and the wooden doors of some of the units on various floors had been pierced with sharp objects. A petrol can was found. Fifteen days later, Choi went to the site with two men and left a telephone number telling the foreman to tell his boss to contact Choi. On April 1, 1992, a fire broke out in the meter room of the building. A piece of rug smelling of kerosene and a tin containing kerosene were found. The court heard that on April 10, 1992, a constable, posing as the person in charge of the victimised company, arranged to meet Choi in a Wan Chai restaurant. Choi, Lee and another man were arrested after they claimed to be members of the Wo Hop To triad society and demanded $120,000 from the undercover policeman. Pui and Chow were later arrested. Choi was jailed for five years for criminal damage, professing to be a member of the Wo Hop To triad society, arson, blackmail and claiming to be a member of a triad society. Defence counsel Mr C. P. Pang, for Choi, had asked for concurrent sentences. Lee, who was found guilty of arson, blackmail and claiming to be a member of a triad society, was jailed for 41/2 years. Chow was sentenced to 18 months for arson. Pui was jailed for 12 months for criminal damage. Pui's counsel Mr David Ma said his client did not damage the doors. Mr Luke McGuinniety, for Lee and Chow, said both defendants had committed the offence out of stupidity.