Nearly two-thirds of textbooks used by international schools in South Korea solely use the name "Sea of Japan" to describe the East Sea, research showed Friday, triggering calls to get local authorities to take action.

According to the research conducted by the Ministry of Education, 24 of 33 related textbooks used at international schools solely used the name "Sea of Japan," while the nine others used both terms.

Ten schools adopted textbooks that stipulate both names, while 16 others used those with only "Sea of Japan."

Seoul claims that textbooks and maps must at least use both names to describe the water. South Korea has maintained the "Sea of Japan" is one of the legacies of Japan's 1910-45 colonization of the Korean Peninsula. Japan registered the name "Sea of Japan" with the International Hydrographic Organization in the early 1920s.

The education ministry said it will make efforts to promote the awareness of the East Sea issue to international school educators so they can more accurate manage teaching materials.

The Academy of Korean Studies said they will also seek to contact the publishers of textbooks and request they use correct terms. (Yonhap)