THE marketing drive has begun to fill one of China's biggest projects . . . a city. It is hoped Sun City will be home for more than 100,000 people when it is completed by the end of the century. It is part of a planned new hi-tech zone in Guangdong Province which the developers want to become the prime gateway to China and, eventually, Asia's top economic centre. Highly competitive science and technology industries will be encouraged to go to the Metro-Huizhou Economic and Technological Development Zone which has been given full support by the central and local government. Commercial centres, luxury housing, and business and manufacturing facilities will make up the main profile of the new city. It is hoped that hi-tech firms and research and development enterprises will base there. Developers, the SanHe Group Co - which reports directly to the Huiyang local government - and China Treasure Enterprise (CTE), a subsidiary of Hongkong based Kiu Yin Investment Co, are the project's controlling investors. They hope the dream of a city of hundreds of thousands of people will be a reality in the near future. The foundations are being laid at the moment. Negotiations are underway with firms in Hongkong and Singapore to set up offices there. Ms Connie Mo, a director of CTE, hoped the area would overtake Asia's four dragons - Hongkong, Korea, Singapore and Taiwan - and become China's prime gateway. ''We called it Sun City because that signals life, productivity and vision,'' she said. ''We want the public to know that it is a good prospect for investment and is the big hope of China.'' Sun City will be a satellite city to neighbouring Huizhou. Initially, the developers will build up the centre and residential areas of the new city. They expect firms to move in and build on the industrial sites. It is 18 kilometres from Aotou port on China's east coast and 90 minutes by hydrofoil to Hongkong. It is within a three-sided valley which is predominantly flat and alongside the Danshui River. The developers are hoping to attract big money foreign investors. They said the residents would be in the high income bracket, running their own businesses and living in luxury accommodation. Citizens will enjoy top quality museums, cinemas, theatres, restaurants and sports clubs. Two water plants are to be built - one serving Sun City alone and the other meeting the requirements of surrounding areas. The local power supply is being upgraded to cope with expected demand. A main telegraph office, local branches and a digital telephone network will be established. Developers predict 20,000 lines will be set up by the end of 1995. The 10-square-kilometre site is well connected to the rest of the region, according to the developers, by several major roads and highways. Huiyang Airport - which is 20 kilometres away - has been upgraded at a cost of 40 million yuan (about HK$52 million). Residents will also have access to the Beijing-Jiujang-Kowloon railway. Land used for hi-tech industrial sites, residential development and commercial and retail units will each take up 30 per cent of the city. The remaining 10 per cent will be used for green space. Sixty per cent of space is available for foreign investors and the rest for the local market. The developers claimed Huiyang County was proving more popular with foreign firms eager for an alternative to the highly developed areas of southern China. They can also still benefit from the financial incentives in the Special Economic Zones of the Pearl River Delta. Ms Mo added: ''We expect Sun City to become a major economy. We have confidence that it will attract major investment and create employment.'' Two sales exhibitions are planned for Hongkong. The first will be in the Queensway Exhibition Hallat Admiralty later this month, followed by an exhibition in New World Plaza at the beginning of May. Kiu Yin Investment established CTE with a view to increasing investment on the mainland. It will be responsible for overseeing the entire plan of Sun City and will provide its managerial services. The SanHe Group started as the Huiyang United Development Group Co in 1992. It was jointly formed by a number of public organisations, including the Huiyang Planning Commission, the National Land Bureau and the People's Construction Bank of China.