A top energy official left Tuesday for Moscow to hold talks with Russian officials over a planned pipeline to carry crude oil from eastern Siberia.
Iwao Okamoto, director general of the Agency of Natural Resources and Energy, is expected to try to sell a Japanese proposal that the pipeline be laid between Angarsk, near Lake Baikal, and Nakhodka on the Sea of Japan.
Okamoto will stay in Moscow until Saturday, agency officials said. His latest visit follows a round of talks in early March.
Japan and China are competing to try to get Moscow to decide in their favor.
China wants the pipeline to be laid from Angarsk to Daqing, an inland city in Heilongjiang Province, northeastern China.
A compromise that Russia is drafting suggests building the Chinese route first, then adding a branch to supply Japan. Japan has said that trying to supply both countries would make it difficult for Japan to receive sufficient supplies.
The Russian government is scheduled to make a decision on the route in May.