Russia threatened on Thursday to ban visa-free travel for Japanese officials to four disputed Pacific islands if they make statements demanding the territories be returned to Japan, reports Hurriyet Daily News.
The renewed tension could set back a fresh drive by the countries' leaders to end a decades-old territorial dispute over the small islands north of Hokkaido which were seized by Soviet troops at the end of World War Two.
The spat over the islands, known as the Southern Kurils in Russia and as the Northern Territories in Japan, has prevented Moscow and Tokyo signing a treaty formally ending hostilities and still hinders efforts to improve relations.
"If for some reason Japanese politicians cannot refrain from making public statements on the subject of the islands after a visit to Russian territory, we reserve the right to limit their participation in such trips," the Russian Foreign Ministry said.
It underlined in a written statement that visa-free travel was permitted for Japanese officials as a "humanitarian act", mainly to enable them to visit the graves of their ancestors.
The ministry made clear it was referring to comments by Ichita Yamamoto, Japan's Minister of State for Okinawa and Northern Territories Affairs, during a visit to the islands and quoted him as saying that his view of "the need to return territories" was reinforced by his trip.