Tokyo (Agencies): Japanese Prime Minister Naoto Kan has demanded the return of disputed Kuril Islands captured by Russia since World War II and called Russian President Dmitry Medvedev visit to these territories as unforgivable outrage.

Terming the islands off Hokkaido as "Japan's northern territories" Kan said the return of these chain of islands was of "extreme concern to Tokyo".

Addressing a large rally, to mark the annexation of these islands by Russia, the Japanese Prime Minister said he would discuss with Moscow to solve the territorial issue, Kyodo news agency reported.

A row has been simmering between Moscow and Japan for a long time over the ownership of the islands and the issue flared recently after Russian President made an unannounced visit to the windswept volcanic islands, located between Japanese island of Hokkaido and Russia's Kamchatka peninsula.

Japan angry over the Russian occupation has refused to sign a post World War II peace treaty with Moscow. The Kuril Islands have been controlled by Moscow after the then Soviet troops stormed into the islands in the final days of the World War II expelling the Japanese residents and settling Russians there.

Kyodo reported the islands were now home to 19,000 people and are rich in gold and silver with an abundant marine life.

Japanese Foreign Minister Seijai Maehara, who is due to make his first visit to Moscow from Thursday, said he would take up the issue of return of the islands with Russian leaders.