SEOUL - As recurring territorial disputes breed bad blood between South Korea and Japan, South Korea is seeking ways to bolster its effective control over a set of disputed islets lying halfway between the two neighbors.

In a move that infuriated South Korea, Japan passed two days ago a dozen new middle school textbooks describing the islets as part of its territory, claiming South Korea, which has effective control over them, is illegally occupying them.

The lonely set of rocky outcroppings in the East Sea have been a source of chronic diplomatic feud between the two countries, whose conflict-ridden relations date back to Japan's brutal 1910- 45 colonial occupation of the Korean peninsula.

South Korea considers Japan's territorial ambition as a sign that it is not entirely repentant of its past as a colonial ruler, and the issue always stokes up nationalistic sentiments in both countries.

South Korea's foreign ministry responded to Japan's latest claim Wednesday with a strongly worded statement condemning Tokyo, demanding it withdraw the decision. The islets, called Dokdo here and Takeshima in Japan, belong to South Korea "historically, geographically and by international law," the ministry said.

Critics have long said South Korea, despite its strong verbal protests against Japan's repeated territorial claim, has not taken any definitive action showing or strengthening its jurisdiction over the islets.

Prodded into action, officials here now say they are looking for ways to bolster the country's presence on the sparsely populated islets.

"We will exercise every right" as a sovereign nation controlling its own territory, foreign ministry spokesman Cho Byung-je said, calling the islets "a place where South Koreans can freely come and go."

In his first official response to Japan's latest reiteration of its territorial ambition, South Korean President Lee Myung-bak also said he will continue working on bolstering the country's effective control over the islets.

"South Korea has an effective control over (the islets), and that sets us apart from others who claim (the islets) are theirs," Lee said Friday in a televised interview.

"South Korea will continue working on strengthening our control over (the islets)," Lee said, arguing against criticism that the government has been lackadaisical in responding to Japan' s repeated claims.

In an effort to demonstrate its control of the islets, South Korea, which has a coast guard unit already stationed there, is now working on reviving a heliport there. A senior official at the ruling Grand National Party argued Friday residential buildings should also be built along with a heliport.

The foreign ministry is also reportedly mulling an old idea of building facilities devoted to marine science studies. Education and science minister, Lee Ju-ho, was to fly to the islets Friday to establish radiation detection equipment there, a clearly symbolic gesture.

These are still small steps, however, with officials remaining cautious about the disputes getting too much international spotlight.

"Some wonder why South Korea is keeping a low profile on this issue, but taking action that is too direct might not be the wisest idea," the president told reporters in the same press conference.

An opposition leader agreed. "South Korea needs wise diplomatic strategies so as not to be tricked by Japan into bringing the issue to the international court," Sohn Hak-kyu, leader of the main opposition Democratic Party, said Friday.