Japan on Monday urged Russia to roll back its ban on former residents of disputed islands after Moscow barred their group from visiting the islets under its control.
Matsuno Hirokazu, the top spokesman for the Japanese government, said Tokyo has lodged a protest with Moscow over the issue.
"The announcement is causing emotional pain for the former residents and their supporters," said Hirokazu, referring to "League of Residents of Chishima and Habomai Islands"-the organization of former residents of North Territories, known as Kuril Islands in Russia.
Tokyo's displeasure came as Moscow Friday designated the group as "an undesirable organization."
"The move is apparently aimed at stepping up pressure on Japan for imposing sanctions against Russia over its invasion of Ukraine," Japanese public broadcaster NHK said.
The disputed islets are under Russian control while Japan claims them.
"The group has worked to raise awareness in Japan for many years and supported efforts between Tokyo and Moscow to conclude a peace treaty," said Hirokazu, calling Moscow's labelling of the group as "extremely one-sided and totally unfounded."
"The former residents of the islands, as they grow older, want the territorial issue of the Northern Territories to be settled, and to visit graves on the islands as soon as possible," he added.
Russia has a territorial dispute over the Kuril Islands with Japan, which it has not signed a peace treaty with since World War II.
At the 1945 Yalta Conference, the Soviet Union agreed to start military operations on the eastern front under an agreement with its Western allies, and in exchange, received some Japanese territories, including the Kuril Islands.
After the war, however, Japan rejected the Soviet Union's sovereignty over the islands.
Due to the dispute, Russia and Japan have never signed a peace treaty and are technically still at war. As both sides claim the territories, the question of Kurils' sovereignty remains uncertain.
