Russia's envoy to Japan said Wednesday that a reported plan by Prime Minister Junichiro Koizumi to visit Russian-held islands claimed by Japan would not solve pending disputes but rather create new problems and would be "unproductive" for bilateral relations.

Russian Ambassador to Japan Alexander Losyukov also expressed reservations over any progress on negotiations for a bilateral peace treaty, including the territorial dispute, as "there is currently no resolution that is acceptable to the public in both countries."

Koizumi has asked government officials and ruling bloc lawmakers to study the feasibility of visiting one of the disputed islands off Hokkaido, possibly by the end of this year, government sources said earlier.