Japan's Foreign Minister Seiji Maehara said on Saturday Tokyo is looking up at an opportunity to participate in joint investment projects in the Kuril Islands with Russia.

"The Foreign Ministry is studying whether it is possible for the proposal [on investment] not to hamper the Japanese judicial position," the minister was quoted by the Mainichi newspaper as saying.

At talks with Maehara in Moscow earlier this month, Russian Foreign Minister Sergei Lavrov said Russia would be pleased to see Japanese, Chinese and South Korean investment in the islands.

Japan then said this would recognize Russia's sovereignty over the disputed islands, which contradicts the Japanese official stance. Tokyo also said investment projects involving third countries would complicate the solution of the territorial dispute.

Japan's continued claim over four South Kuril Islands has prevented Moscow and Tokyo from signing a formal peace treaty to end World War II hostilities. Iturup, Kunashir, Shikotan and Habomai, known in Japan as the Northern Territories, lie at the end of a chain stretching from Russia's Kamchatka Peninsula to the Japanese island of Hokkaido.

Tensions escalated in November last year when Russian President Dmitry Medvedev visited one of the disputed islands, an act Japanese Prime Minister Naoto Kan criticized as "inexcusable rudeness."