SEOUL, April 7-- South Korea on Tuesday denounced Japan's yearly diplomatic paper as "history-regressive," as the Japanese government repeated its territorial claims to Dokdo islets, called Takeshima in Japan.

"Today, it (the Japanese government) repeated its history- regressive action by presenting to the Cabinet, the Diplomatic Blue Paper, including an unjustifiable claim over Dokdo and the victims of wartime sex slavery," the South Korean Foreign Ministry said.

The statement came after Japanese Foreign Minister Fumio Kishida submitted the paper, which said Dokdo is "an inherent part of Japanese territory" according to historical facts and international law. The paper will be published in English for the first time in nine years to promote its claim overseas.

The ministry stressed that Dokdo was the first victim of Japan' s imperialistic plundering of the Korean Peninsula, a historical fact that cannot be erased and revised, adding that many Korean women were forced into sex slavery for Japan's military brothels during the World War II, inflicting "indescribable" pains and sufferings to them.

Citing German Chancellor Angela Merkel's remarks, the ministry urged Japan to ask itself about why the postwar Germany is being respected by the international society.

On Monday, Japan's Education Ministry approved 18 textbooks on history, civics and geography that will be used as teaching materials from next year for middle schools.

Among the total, 13 textbooks stated that South Korea "has illegally occupied" the islets, tripling the number just four years ago. The number of textbooks calming that Dokdo is "an inherent part of Japanese territory" rose from nine to 15 in the same period.

Dokdo is comprised of two main islets and a group of smaller rocks, lying 87 km east of the South Korean island of Ulleungdo. The islets have been administered by South Korea since it stationed border guards there in 1954.

The South Korean education ministry said in a separate statement on Monday that new Japanese textbooks betray Japan's intention of aggression into Dokdo.

The South Korean Foreign Ministry summoned Japanese Ambassador Koro Bessho to protest against Tokyo's "provocative" actions.