Prime Minister Keizo Obuchi and Li Ruihuan, a visiting senior Chinese Communist Party official, reaffirmed Friday that their two countries will further strengthen ties based on firm mutual trust, a Foreign Ministry official said. Li, the No. 4 figure in the Politburo Standing Committee, the Communist Party's executive organ, is in Japan on a nine-day visit that ends Thursday. Li's visit is part of a high-level political dialogue between Tokyo and Beijing that began with Obuchi's visit to China in July. Li's trip also paves the way for Chinese premier Zhu Ronji's expected visit in 2000. During talks Friday evening at the Prime Minister's Official Residence in Tokyo, Li said that since Japan and China are expected to assume greater responsibility in the Asia-Pacific region, they should further cooperate in political, economic and other fields, the official said. Regarding a bilateral fisheries pact, which was signed two years ago but has yet to take effect, Obuchi expressed concern over the delay, the official said. Although the Nov. 1997 agreement replaced a previous 1975 pact in line with a new international law of the sea, it has yet to come into force because of overlapping economic zones. The two nations' 200-nautical mile exclusive economic zones, which they are permitted to declare under the U.N. Convention on the Law of the Sea, overlap in the East China Sea. Under the 1997 pact, Tokyo and Beijing determined jointly controlled sea boundaries around the disputed area, but negotiations on specific activities within the boundaries have not been finalized. Li said that he is optimistic that China and Japan will be able to resolve the issue because their relationship is based on firm mutual trust, adding that he will consult with Chinese fisheries authorities on the matter, the official said. Earlier in the day, Li had talks with Foreign Minister Yohei Kono, who also expressed concern over the fisheries pact, the official said. Kono told Li that although Sino-Japanese relations have been excellent as a whole, the fisheries pact has raised grave concerns among Japanese fishermen, the official said. Meanwhile, Kono and Li reaffirmed efforts to promote exchanges of the two countries' lawmakers to further enhance the understanding of both societies, the official said.