Japanese officials say they are protesting a planned visit by the Russian Prime Minister to an island which is controlled by Russia and claimed by Japan.
Officials in Etorofu Island say Dmitry Medvedev is making arrangements to visit the island via Sakhalin as early as August, and that local officials are making preparations.
They say the Prime Minister is considering inspecting a seafood processing factory and a hot spring facility. He may also check on the progress of the construction of schools and roads.
It would be the fourth visit by Medvedev to any part of the four Russian-controlled islands claimed by Japan. In 2010 while president, he became the first Russian leader to visit one of the four islands.
The Japanese government maintains the islands are an inherent part of Japan's territory. It says the islands were illegally occupied after World War Two.
The Japanese Foreign Ministry says any visit by a senior Russian official to the islands is not compatible with Japan's position on the territorial issue.
A Japanese official told reporters on Wednesday that the government is urging the Russian side to cancel the planned visit.
The territorial issue has prevented the countries from signing a peace treaty, even though the second world war ended more than 70 years ago. Japanese officials say the planned visit by Medvedev could have a negative impact on the ongoing peace treaty negotiations between Tokyo and Moscow.