GUANGDONG'S foreign economic relations witnessed unprecedented success last year, with both trade and investment reaching record levels, according to a senior official. The director of the Guangdong Provincial Commission of Foreign Economic Relations and Trade, Mr Xu Dezhi, said the province's exports last year were more than US$18.45 billion, up by 31.8 per cent compared with 1991. Guangdong's exports were a quarter of the national total, the seventh consecutive year it had been China's top trading province. Mr Xu said Guangdong's imports also witnessed a huge surge. The province imported $10.64 billion worth of products last year, an increase of 25 per cent compared with 1991. ''This is more than 100 times the total imports recorded in 1978, which was only US$100 million. I have never experienced better performance than last year in my 28 years in foreign trade.'' Mr Xu said last year was successful not only because trade had reached record levels, but also because efficiency of enterprises involved in foreign trade had improved. Before 1991, China's foreign trade firms were subsidised by the state, but last year, Guangdong's foreign trade enterprises not only could become self-sufficient, but started to make a profit. Export products have shifted from agricultural products and raw materials to industrial products and processed goods, which now made up 82 per cent of exports. An increasing amount of exports were hi-tech products, such as laser discs, television sets, audio systems and other complex electronic equipment, according to Mr Xu. Meanwhile, Guangdong had also achieved considerable results in diversifying its export markets. While the traditional Hongkong and Macau markets increased by 34 per cent, other markets were up 35.4 per cent. As far as foreign investment was concerned, Mr Xu said a 12,900 foreign investment contracts were signed last year, involving some $19.84 billion, up 242 per cent compared with 1991. Projects started so far this year involved some $4.8 billion, an increase of 88.2 per cent compared with last year. Mr Xu said it was encouraging that new investments had shifted from coastal areas to inland and mountain areas and that new investments had shifted from manufacturing to service industries. In 1993, Mr Xu said Guangdong would take every step to maintain its leading position in foreign trade among various provinces and cities in China. ''Although reform was implemented in Guangdong much earlier than other areas of China, other places are catching up with us, and some of them even have better conditions. ''If we fail to keep our momentum, will begin to lag ging behind other provinces and cities, and lose the momentum in maintaining global markets,'' he said. not to mention mainntaining competitive in the global market,' he said. ''The province will grant foreign trade firms more autonomy, improve the investment environment and revamp the existing foreign trade system. He added that some of the foreign trade enterprises would be allowed to be listed on the local stock market or stock exchanges in Hongkong or other countries.