A top aide to President Lee Myung-bak on Sunday arrived at a South Korean island in the East Sea in an effort to thwart a planned trip by three Japanese lawmakers seen as an attempt to reassert Tokyo's claim to the Korean territory.

Lee Jae-oh, a lawmaker of the ruling Grand National Party (GNP) who doubles as minister for special affairs, arrived on Ulleung Island Sunday, and plans to visit Dokdo, about 90 kilometers east of Ulleung, on Monday.

Before taking the boat bound for Ulleung, Lee said, "I will let the world know that Dokdo is our land, and I will be on the guard duty there to show our strong determination."

Lee had announced his plans earlier Sunday on his Twitter page.

His four-day trip comes as the three Japanese lawmakers of the conservative Liberal Democratic Party vowed to press ahead with their planned trip to Ulleung Island, despite Seoul's warnings that their entry will be banned at the airport here and their safety will not be guaranteed. The legislators are due to arrive in South Korea on Monday for a four-day trip.

"I will stay there until the Japanese lawmakers leave," wrote Lee, known as President Lee's right hand. "The descendants of war criminals are daring to test the Republic of Korea. I will show them clearly that there is no land here for them to set foot on."

Lee's trip is expected to include meetings with local residents and Coast Guard officials stationed on Dokdo as well as public condemnations of Tokyo's repeated claims to the rocky outcroppings that have been a key source of tension between the sides since Korea gained independence from Japan's 1910-45 colonial rule. South Korea dismisses Japan's claims as nonsense, saying it regained control over all of its territory, including Dokdo.

Lee made a similar trip to Dokdo in April.

Meanwhile, Rep. Lee Ju-young, the GNP's chief policymaker, condemned the Japanese legislators' move as "another act of aggression." Speaking to reporters at his party headquarters earlier in the day, he said the visiting lawmakers were no different from assassins without knives, as they were "breaking South Korea-Japan relations into two."

"If they go ahead with their visit, it will only damage Japan's reputation and strengthen the South Korean people's will to guard Dokdo," the policymaker said. (Yonhap News)