Russia's top prosecutor paid a visit Friday to parts of the Moscow-held, Tokyo-claimed islands off Japan's northernmost main island of Hokkaido, islanders told Kyodo News.
Prosecutor General Igor Krasnov became the first senior Russian government official to visit the disputed islands, called the Northern Territories in Japan and the Southern Kurils in Russia, since Japanese Prime Minister Yoshihide Suga took office last month.
The rare visit by Moscow's top investigative official to Kunashiri and Shikotan islands was slammed by Tokyo, with Chief Cabinet Secretary Katsunobu Kato saying it was "unacceptable" and a protest had been lodged.
In August, Russian emergencies minister Yevgeny Zinichev also traveled to Kunashiri Island.
Krasnov held talks with local prosecutors and residents on the two islands, while arrangements are being made for a visit to Etorofu Island, according to sources close to the matter.
As part of his trip to the country's Far East, Krasnov on Thursday visited Yuzhno-Sakhalinsk, the capital of the Sakhalin region, which has jurisdiction over the island group, becoming the first top prosecutor to do so in 20 years.
He offered flowers at a monument dedicated to soldiers of the former Soviet Union who died in operations on the Kuril Islands, which were under Japan's control until the final stages of World War II in August 1945, and elsewhere.
The decades-long dispute over the island chain that also includes the Habomai islet group has prevented the two countries from signing a postwar peace treaty.
The four islands were seized by the Soviet Union following Japan's surrender in 1945. Tokyo argues the annexation was illegal and demands their return, while Moscow says it was a legitimate outcome of the war.
Also on Friday, Foreign Minister Toshimitsu Motegi and his Russian counterpart Sergey Lavrov agreed over the telephone to promote talks toward signing the treaty and to push joint economic activities on the disputed isles as a way to build mutual trust, according to the Japanese Foreign Ministry.
The two, in their first phone talks since Suga took office in mid-September, did not discuss Krasnov's visit to the isles, an official at the ministry said.
Suga has expressed his readiness to promote negotiations on the territorial dispute, which his predecessors including Shinzo Abe failed to put an end to, based on a 1956 joint declaration between Japan and the Soviet Union.
In 2018, Abe and Russian President Vladimir Putin agreed to advance negotiations based on the declaration stipulating that Moscow will hand over the two smaller islands -- Shikotan and Habomai -- to Tokyo after a peace treaty is concluded.© KYODO