An undercover policeman was made to pay 16 times the price he was quoted for abalone and ginseng at a Mongkok shop after being surrounded by at least three men. The shop is one of five named by the Consumer Council early this year for using misleading advertisements and unscrupulous tactics to pressure customers into buying goods, police said. The officer was sent to the Nathan Road shop yesterday morning after police received more than 20 complaints. Police said prices were indicated using large print whereas the unit of weight used - taels - was difficult to read. 'Our officer was told by staff that the price of $358 was for a catty. Afterwards the officers bought a certain amount of abalone and ginseng and the product was sliced,' Chief Inspector Lo Kai-wah from the Kowloon West regional crime unit said. 'The officer was told the marked price was in fact for a tael and not a catty, and was then asked to pay between $4,000 and $5,000. 'Staff claimed the officer could not leave the store unless the bill was paid. 'When our officer tried to leave, three or four staff used their bodies, arms and hands to stop him from leaving.' A catty is equal to 16 taels, so the officer had to pay 16 times the amount he had been quoted. After the undercover officer paid the bill seven staff, including the person in charge of the shop, were arrested. Last night, they were detained at the Kowloon West regional crime unit headquarters in Kowloon City for further investigation. The five dried seafood stores named by the Consumer Council earlier this year were Well Ultra International, Yuen Mong Tong, Wah Chong Ginseng & Sea Products, Hung Hing Ginseng and Chung Ngai Ginseng Seafood Products. William Archambaud-Chao from the Consumer Council welcomed the police action. He said complaints against Chinese medicine and dried seafood shops from residents and tourists soared from 146 in 1996 to 340 last year. In the first nine months of this year, there were 304 complaints. Mr Archambaud-Chao said the unscrupulous tactics were damaging Hong Kong's reputation as a shopping and tourist paradise. He urged consumers to stay alert to such practices. Mr Lo said more undercover agents would be deployed to tackle unscrupulous selling methods, if necessary.