In a move that has been repeated all too often, South Korea on Wednesday railed against Japan's latest territorial claim to a set of disputed islets lying half way between the two Asian neighbors.

The islets have been a source of recurring diplomatic feud between South Korea and Japan, whose conflict-ridden relations date back to Japan's brutal 1910-45 colonial occupation of the Korean peninsula.

"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 strongly worded statement was issued shortly after the Japanese government approved a dozen school textbooks describing the set of rocky outcroppings in the East Sea, called Takeshima in Japan, as its territory, its newest attempt.

The islets have been controlled by South Korea, which considers Japan's territorial ambition as a sign that it is not entirely repentant of its past as a colonial ruler. Besides the claims to the islets, the new textbooks also "justify and beautify" Japan's colonial occupation, the foreign ministry said.

Repeated calls by leaders of the two countries for "forward- looking relations" have always paled in the face of recurrent territorial disputes, which are often quick to stoke up nationalistic sentiments in both countries.

This time around, the renewed claim comes as a particularly bigger shock to many South Koreans, whose donations to the neighboring country scrambling with the aftermath of the earthquake and tsunami have reached a record high in its foreign aid history.

Some now deride the on-again, off-again bickering as an "annual event," but the foreign ministry spokesman said the conflict will have to repeat itself unless Japan resolve the outstanding issues. "Japan is solely responsible for the problem, because it created the problem," Cho Byung-je told reporters.

Still, bad blood surrounding the disputes should not discourage South Korea's efforts to help its quake-hit neighbor get back on its feet, Cho said. "We believe care and support that has been poured into Japan is a reflection of our love for humanity, and hope the textbook issues wouldn't change that."

Discussions are currently underway here as to how to diplomatically address the thorny issue, but the South Korean government is not considering at this point summoning its top envoy to Japan back home in protest, according to the foreign ministry. South Korea, which has a coast guard unit stationed on the islets in a show of its effective control of them, is reportedly planning to revive a heliport there in response to Japan's renewed sovereignty claim.

The new school Japanese textbooks will be in use starting April.