SEOUL - South Korea on Wednesday railed against Japan's latest territorial claim to a set of disputed islets lying halfway between the two Asian neighbors, a source of chronic diplomatic feud.

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"The government strongly protests the authorization of middle school textbooks describing Dokdo as part of the Japanese territory, and we demand Japan immediately withdraw its decision," Seoul's foreign ministry spokesman Cho Byung-Je said in an official statement.

The islets belong to South Korea "historically, geographically and by international law," the spokesman added. "We remain firm in our stance that we will deal resolutely with any attempt by Japan to damage our sovereignty over Dokdo."

The remarks came shortly after the Japanese government approved a dozen textbooks describing the set of rocky outcroppings in the East Sea, called Takeshima in Japan, as its territory. The renewed claim alleges South Korea's current territorial control over the islets is "illegal".

The new Japanese textbooks, which Seoul says also "justifies and beautifies" historical views about the country's brutal history of colonial occupation, will be in use at schools starting April.

South Korea is currently not considering summoning its top envoy to Japan back home in protest, according to the foreign ministry.