MACAU'S Hang Sang Bank has become the first bank in the enclave to offer flexible yuan exchange rates to the public, according to the Lusa news agency. The move follows the Chinese Government's decision to allow travellers to carry up to 6,000 yuan through its borders from the beginning of this month. The bank's yuan rate yesterday stood at 112 yuan buy and 117 sell per HK$100, compared with the official fixed rate of 74.05 yuan per $100. The bank is offering postal and telegraphic transfer services in yuan and Hongkong dollars with China through its mainland agent bank, the Industrial and Commercial Bank of China. The Macau branch of the Bank of China is preparing to offer similar services in the near future and other banks are expected to follow. Meanwhile, a senior Chinese official has described relations between China and Portugal as ''very good''. Chinese External Economic and Trade Minister Mr Li Lanqing made the comment after meeting Portuguese Commercial and Tourism Minister Faria de Oliveira in Beijing. Mr Oliveira led a 36-member trade mission of businessmen and bankers seeking to expand trade with China. It is the largest Portuguese trade mission ever to visit China. Mr Li said that after Premier Li Peng's visit to Portugal last year, relations between Portugal and China in areas of commerce had developed.