MAYOR of San Francisco Willie Brown met his Shanghai counterpart Xu Kuangdi yesterday to celebrate the 17-year-old sister city agreement. Accompanied by a 50-member delegation of San Francisco civic and business leaders at a ceremony in Shanghai's municipal government headquarters, Mr Brown praised the 'long and enduring friendship'. He said the relationship had borne more fruit than many such relationships because of the rise of Shanghai's successive mayors into the top echelons of China's central Government. Ties had been further enhanced by the marriage of Shanghai party secretary Huang Ju's daughter Daphne, 28, and James Fang, a member of a prominent San Francisco publishing and political family, he added. Sister-city ties were established in 1980 under Wang Daohan , who now heads the mainland's Association for Relations Across the Strait, and continued through the Shanghai mayoral stints of President Jiang Zemin and Vice-Premier Zhu Rongji . Although several Western diplomats said it was an unusual breach of protocol for a mayor to be received by a head of state, Mr Brown met both President Jiang and Mr Zhu during the Beijing leg of his trip. Since leaving Shanghai, Mr Jiang and Mr Zhu have paid close attention to the San Francisco connection and helped to ensure that it survived when Sino-US relations soured after the Tiananmen massacre. A management training programme in which Shanghai students work and study in San Francisco was, according to Sun Yuanxin , director of the programme and a professor at Shanghai University, the only bilateral programme not to break up during 1989. 'This shows how much importance the centre places on this relationship,' Mr Sun said. Mr Wang told graduates of the programme: 'Relations between the two countries have entered a new stage with a relaxation of tensions.' A Shanghai-based Western diplomat concurred, saying this week China and the United States might be 'on the brink for the first time since 1972 of establishing a truly normal relationship'. Mr Brown is due to arrive in Hong Kong today for a four-day visit. He and his party will be briefed by the Hong Kong Government on handover arrangements and will tour the airport complex at Chek Lap Kok before continuing to Taiwan.