Hong Kong's Secretary for Constitutional and Mainland Affairs Stephen Lam Sui- lung arrived in Taipei Thursday for a three-day visit. Lam, who is being accompanied on his visit by several other officials, has become the highest-ranking Hong Kong official ever to visit Taiwan since the former British colony reverted to Chinese sovereignty in 1997. Lam, the top Hong Kong official in charge of Taiwan-related affairs, told local reporters that the main purpose of his visit is to promote trade and economic cooperation between Taiwan and Hong Kong. Lam was scheduled to meet Friday with Fu Dong-cheng, vice chairman of Taiwan's Cabinet-level Mainland Affairs Council, on measures to boost exchanges and cooperation in the fields of economics, trade and culture. He was also expected to pay a visit to the Taipei city government that same day for talks with Taipei Deputy Mayor Wu Ching-chi on possible cooperative projects between the two cities. 