Beijing has expressed concern about a Taiwanese leader's visit to Japan, saying it opposes any official exchanges between Taipei and Tokyo. John Chang Hsiao-yen, secretary-general of Taiwan's ruling Kuomintang Party, will make a five-day visit to Japan starting tomorrow, Taiwan's Central News Agency said. Mr Chang will join a seminar on Thursday attended by political and financial leaders from Asian nations. Mr Chang said the trip was a non-official one, but Taiwan sources said one of Mr Chang's missions was to lobby Japan officials not to sacrifice Taiwan interests due to pressure from Beijing. President Jiang Zemin has postponed his own trip to Tokyo - which was to have begun on September 6 - due to the flood crisis at home. Mr Chang, meanwhile, has arranged to meet Yoshiro Mori, secretary-general of Japan's ruling Liberal Democratic Party, to explain Taiwan's position on relations with the mainland. Foreign Ministry officials in Beijing expressed concern about the reported meeting and said: 'Japan should have a more progressive understanding of the 'One China' concept.' It is expected that Beijing will seek further assurance from Japan on non-intervention in Taiwan affairs during Mr Jiang's trip. Japanese officials have said Japan will not issue a statement to that effect as it has done so already, in 1972 and 1978. Japanese Prime Minister Keizo Obuchi yesterday wrote to Mr Jiang saying he was sorry to learn of the devastation caused by floods on the mainland. Mr Obuchi said he hoped Mr Jiang's visit could be rescheduled soon. Foreign Ministry officials in Beijing said meetings to set a new start date for the state visit had not yet begun. Tokyo has given 250 million yen (HK$13 million) in flood aid since July 3.