Four people have been jailed for up to 18 months by the District Court for bribery and fraud over the supply of frozen salmon and eel to Japanese restaurants and sushi stalls in supermarkets.

Kana Transa Group shareholder and director Chan Kin-chung, 41, was sentenced to 18 months and fined $11,000. He admitted to five counts of fraud and one of offering advantages to an agent.

Fellow shareholder and director Lau Tat, 39, pleaded guilty to three counts of fraud and was jailed for nine months.

Former Tokyo Sushi chefs Tam Wai-man, 28, and Liu Tak-keung, 30, each received six-months' jail for fraud.

Kana Transa was a wholesaler of seafood supplying frozen salmon and eel to Japanese restaurants and supermarket stalls. Tam and Liu were employed by Five Harvest as chefs of Tokyo Sushi. They were responsible for placing purchase orders with suppliers and were required by Tokyo to weigh the food delivered and check the invoices.

Since 2005 the four defendants had agreed among themselves to exaggerate the weight of salmon stated in the invoices issued by Kana Transa to Tokyo. Between 2007 and September 2008 Chan and Lau had overstated the weight of frozen fish in the invoices and created bogus invoices for food delivered to the sushi stalls at the Whampoa and Kornhill branches of PTC-Nakajima Suisan (Hong Kong). The inflated amount was about $50 per box of frozen fish or food.

Chan also offered two employees of the two sushi stalls cash rebates ranging from $3,000 to $10,000 on numerous occasions, depending on the value of purchase orders.

Chan and Lau used similar fraudulent means to deceive two other Japanese restaurants, Sapporo Ramen Domon and Dream Maker Shichi Fuku San, between 2007 and September last year.