SEOUL - South Korean President Lee Myung-bak instructed the foreign ministry Wednesday to notify Japan that the planned visit by four Japanese lawmakers to a South Korean island might put their safety at risk, an official here said.

"The president ordered the foreign ministry officially notify Japan of possible safety concerns," presidential spokesman Park Jeong-ha told reporters in a briefing, denying a report that Lee ordered officials to send back the Japanese lawmakers when they arrive at a local airport.

Four members of Japan's conservative Liberal Democratic Party are planning to visit the South Korean island of Ulleung, located some 90 kilometers away from a set of islets claimed by both countries.

Lawmakers and local civic groups are strongly opposing the move, with the chairman of South Korea's ruling Grand National Party claiming the visit would amount to a denial of the country's constitutional order.

Seoul's special affairs minister, Lee Jae-oh, has also repeatedly called for rejecting the Japanese lawmakers'attempt to enter South Korea, citing the country's immigration control law.

The move is seen as the latest in a series of attempt by Japan to lay territorial claims to the rocky islets lying halfway between the two countries, known as Dokdo here and Takeshima in Japan.

The lonely set of outcroppings in the East Sea has been a source of recurring diplomatic row between the two Asian neighbors, whose conflict-ridden relations date back to Japan's brutal 1910- 45 colonial occupation of the Korean peninsula.

South Korea says the islets belong to the country "historically, geographically and by international law," while Japan describes the tiny islets as part of its territory in its school textbooks and official documents.

The potential visit by the four conservative lawmakers was reportedly prompted by the recent high-profile test flight to the disputed islets by the country's flagship airline.

In response to the demonstration flight by Korean Air's first Airbus A380, Japan's foreign ministry then instructed its officials not to fly with Korean Air for a month, calling the test flight "a violation of Japan's airspace".

The measure triggered angry responses here in South Korea, which views Japan's resurgent territorial ambition as a sign that it is not entirely repentant of its past as a colonial ruler.

The boycott against a private corporation could possibly run counter to international diplomatic customs and World Trade Organization rules, officials here have said.

South Korea has a coast guard unit stationed on the disputed East Sea islets, a show of its effective control.

Its Navy, meanwhile, recently announced a plan to expand the size of its air base on Ulleung Island by threefold, a bid to better guard the territorial waters surrounding the disputed islets.