The Japanese government and civic groups on Tuesday criticized Russia for its "illegal occupation" of disputed islands off Hokkaido in a rally demanding their return, with Tokyo using the phrase for the first time in five years following a deterioration of bilateral ties over Moscow's war in Ukraine.

"It is completely unacceptable that the Northern Territories have yet to be returned since the Soviet Union's illegal occupation of them 77 years ago," a statement adopted during the annual event in Tokyo said in reference to the islands, which Russia calls the Southern Kurils.

Prime Minister Fumio Kishida speaks in Tokyo on Feb. 7, 2023, during a rally seeking the return of four Russian-held, Japanese-claimed islets off Hokkaido, known as the Northern Territories in Japan and the Southern Kurils in Russia. (Kyodo)

The territorial row has prevented Tokyo and Moscow from concluding a postwar peace treaty.

The government-sponsored event was held for the first time since Russia launched its war against its western neighbor on Feb. 24 last year.

Japan has imposed punitive sanctions against Russia over the aggression, prompting Moscow since March last year to suspend the decades-old peace treaty negotiations and bilateral visa-free exchange programs, including one that allows Japanese former residents to visit the graves of their ancestors on the islands.

Prime Minister Fumio Kishida expressed hopes for a resumption of such exchange activities between the two countries, describing the goal as "one of the top priorities" in Japan-Russia ties.

He also said the government maintains its stance that it will seek to "resolve the territorial issue with Russia and sign a postwar peace treaty despite the current severe state of bilateral ties."

The ceremony has been held every year on "Northern Territories Day," which falls on Feb. 7. On the same day in 1855, Japan and Russia concluded a Treaty of Commerce, Navigation and Delimitation, drawing a national border that put the four islands inside Japanese territory.

In 2019 and 2020, the rally's statement did not use the phrase "illegal occupation," apparently to avoid increasing tensions with Moscow. Then Prime Minister Shinzo Abe had made resolving the dispute one of his top ambitions.

But in the following two years, after Abe left office, the statement's wording was revised to call Russia's presence in the islands an "occupation without legal basis."

Japan says the Soviet Union illegally seized the islands -- Etorofu, Kunashiri, Shikotan and the Habomai islet group -- soon after Japan's surrender in World War II on Aug. 15, 1945. Russia claims the action was legitimate.

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