Tokyo and Riyadh have failed to narrow their differences in their latest negotiations over the renewal of Arabian Oil Co.'s drilling rights in a major Saudi Arabian oil field, International Trade and Industry Minister Takashi Fukaya said Tuesday. Fukaya made the remark in reference to a two-day governmental powwow that ended Monday in Riyadh, in which Saudi Arabia urged Japan to fund its construction of a 1,400-km mining railway. Japan has repeatedly rejected the request. "There seems to be a gulf between Japan and Saudi Arabia," he said. "The situation is not very promising."