The pilot scheme to control tariff-free raw materials imports will be extended to 28 cities from next week. Liao Guoji , deputy director of the Guangdong Foreign Trade and Economic Co-operation Commission, said one city in each of the 25 provinces or autonomous regions in China would join the scheme from April 1, in addition to the three pilot cities. The duty security deposit system, adopted last November, aimed at preventing the loss of tariff income when raw materials imported under tariff-free contracts for processing and assembly lines found their way to the domestic market. Mr Liao said Nanhai would be the second pilot city in Guangdong to launch the security system. The deputy director of Huangpu customs in Guangdong, Fang Meiguang, said that in Dongguan, 8,406 contracts had been registered to the deposit system by the middle of this month. Mr Fang said China would revise the pilot scheme when most of these contracts were concluded by May. Last year, Guangdong exported value-added products worth a total of about US$10 billion - which accounted for 80 per cent of the province's total exports.