South Korea expressed regret Friday about Japan's official reference to a decades-old territorial dispute, even though Tokyo's new government has apparently softened its stance on the issue.
Seoul's foreign ministry was responding to a Japanese education handbook released earlier in the day.
The manual calls for high school teachers to tell pupils that Japan is locked in a territorial dispute with South Korea over a tiny island chain known as Dokdo in Korea and Takeshima in Japan.
South Korea controls the islands in the Sea of Japan (East Sea) and insists its ownership is incontestable.
"Whatever claim the Japanese government makes, our government stresses the position once again that no territorial dispute exists between the two sides," ministry spokesman Moon Tae-Young said in a statement.
The revised educational guidelines inject a wrong perception into Japan's future generation, he said, describing the move as regrettable.
Japan claimed the islands in 1905 and went on to annex the Korean peninsula from 1910 until its World War II defeat in 1945. South Korea says its ownership dates back centuries.
South Korean officials quoted by Yonhap news agency noted that Japan's education ministry did not directly mention Dokdo in the new document.
The handbook merely says teachers "need to deepen the understanding on territorial issues by providing accurate information based on the Japanese government's proper claim and their study at junior high school".
But Japan said the decision not to explicitly refer to the small rocky outcrops did not mean Tokyo had stopping asserting its sovereignty.
Seoul reacted angrily last year to Japanese guidelines issued for junior high schools saying students should have a "deeper understanding" of Tokyo's claim over the islets, known as Takeshima in Japan.
A new teaching manual issued Friday for high school students says that study of Japanese territories "should be based on junior high school education."