The Japanese government has again claimed Korea's easternmost Dokdo islets as its own territory, this time in Tokyo's latest diplomatic bluebook which was released Tuesday.

Seoul's Foreign Ministry says the annual document of Japan's foreign policy approved by Japan's Diet states that Dokdo is Japanese territory historically and under international law.

The Korean government expressed regret over the move especially in the year that marks the 100th anniversary of the Japanese annexation of Korea. It summoned Reiichiro Takahashi, deputy chief of the Japanese Embassy in Seoul, to file an official complaint.

Cheong Wa Dae spokesman Park Sun-kyu said Japan's latest move was "very disappointing" and Korea will not give in to any attempt to claim sovereignty over Dokdo.